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OCTOBEH 1966 
A Sixth Anniyersary 60 f 










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A 3-band S5B Transceiver Kit for $189.95 

An Electronic Keyer Kit for $49.95 

A Solid-state AC Power Supply Kit for $79.95 



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MQO«l- 




who else but EICO 



Pro atl the way, from concept to execution — that's what ham editors say 
about EICO. Critical customers agree, and iilce the low price, too. 

They've made the 753 kit, for example, the industry's hottest 

seller. And the new 717 Keyer seems headed for the same fate. 

■Highlights of both give you some inkling why: 



'The E(CO 753 }s a compfete S-band 
transceiver^ offering SSB/AM/CW oper- 
ation with conservatively fated 200 watts 
PEP on all modes (rated for maximum 
efficiency rather than maximum possible 
Input power). A new Silicon Solid State 
VFO provides full coverage of the 80, 40, 
and 20 meter bands. Assembly is made 
latter and easier by VFO and IF circuit 
boards, plus pre*assembfed crystal lat- 
tice filter. Rigid construction, compact 
size, and superb styling make this rig 
equally suited for mobile and fixed sta- 
tion use. The EJCO 753 is at your dealer 
now, in kit form and factory-wired, 

FEATURES: High level dynamic ALC pre- 
vents ffat-topping even with extreme 
over-modulation. Automatic carrier level 
adjustment on CW a AM. Receiver offset 
tuning (10 kq bandspread) Without alter- 
ing transmit frequency. Front panel se- 
lected STANDBY, VOX, or P-T-T opera- 



tion. ifnique ball drive provides both 6:t 
rapid band tuning and 30:1 verriier band- 
spread wrth single knob. The Model 753 
is an outstanding value factory wired at 
$299.95 

EICO Model 751 AC Supply/Speaker 
Console: Provides all necessary operat- 
ing voltages for Model 753. Incorporates 
PM Speaker^ conservatively rated com- 
ponents and silicon rectifiers for mini- 
mum heat and extended trouble-tree life. 
Includes interconnecting plug-in cables. 
Kit f 79.95 Wired 1109.95 

SPECIFICATIONS: Output Voltages: 750 
volts DC at 300ma, 250 volts DC at 170ma 
— too volts DC at 5ma, 12.6 volts AC at 
4 amps. INPUT VOLTAGE: 117V AC. 

EICO Model 752 Solid State Mobtle 
Power Supply: (Not Shown). For use with 
12 volt positive or negative ground sys- 



terrts. Fulfy protected against potanty 

reversal or 'overload. Output voltages 
identical to Model 751, Input voltage 
11-14 volts DC. 

Kit $79.95 Wfred $109.95 

The ideal accessory for the CW ham— 
the fully automatic 717 Electronic 
Keyer, It provides self-completrng clean- 
cut dots, dashes, and spaces accuratei/ 
timed and proportioned from 3 to 65 
WPM in four overlapping swrtch-sel acted 
ranges with vernier control of aM speeds 
within each range. Matches EICO 753 in 
appearance to make it a perfect table- 
top companion unit. 

FEATURES: Output Contacts - 25 voH- 
ampere dry-reed SPST relay. Built-in ad- 
justable lone and volume osciHaTor with 
a 3 X 5 inch speaker for monitoring. Can 
be used as a code practice oscillator 

Kit $49.95 Wired $69.95 



for FREE catalog and Amateur Radio brochure write to EICO 131'0t 39th Ave., 

73^10, flushing. New York 1 1352 



EICO 



73 Ma 



gazine 



pyne Green W2NSD/1 
blisher 

I 

I 

ul Franson WAICCH 

itor 

I. 

n Fisk WA6BSO 
chnical Editor 

ck Morgan W0RA 
Ivertising Manager 

tober 1966 

ver by Sid WiHis 



XLIII, No. 1 



ADVERTISING RATES 



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% P 



IX 

$298 

1 55 

80 

42 

23 



$281 

147 
74 

40 
22 



12X 
$264 
139 
72 

38 
21 



fo G%\m chorge for second color 
red, usually) or bleed on full 
»age ads. If you're interested in 
idverHsing to homs^ get our full 
ate cord ond other information 
roin Jock Morgan W{3IIA* 



Magazine is publiilied monihly by 
Inc*, Peterboroygh, N. H, 034 5S. 
e phone is 603-924-5873, Subscript 
ti rates S4,00 per year, ¥7.00 two 
in, SIO three years world wide. Sec- 
J class postage is paid at Peierbor- 
?h, New Hampshire and at addiUon- 

matlmg oQict^s. Prtnled in Bristol, 
nn,, U.S.A. Entire contents copy- 
ht 1966 by 73. Inc. Pcstmasters^ 
ase send form 3S79 to 73 Magazine, 
tcrborougfa, New Hampshire. Why 
t make a DX friend of yours happy 
Ji a gift subscnption to 73? 



TOBER 1966 



WAICCH. 



Integrated Circuifs ,..*,,.,..._ 

How will they affect you? 

El Marrinero . . W6BLZ. - . . • . 6 

An inexpensive eighty meter SSB transceiver. 

Two Tubes for Two K9EID .,-.-. 16 

SSB on two with two tubes and a twenty meter transceiver. 

432 MHz Transmitting Converter ..••,. .K6R!L, . i » . , 18 
Not too expensive or hard to build. 



A Two-Meter FET Converter *.,.,,... K6HMO 
Low noise^ low cost and low cross modulation. 



22 



Electronic Thermometer .,..,,. K5ILG* . . . . • 26 

Make sure that your linear doesn't cook* 

Controlled Avalanche Silicon Rectifiers W9EGQ 26 

There's no need for those shunting capacitors ond resistors. 



« • • « 



Telegraph Keys ...*.. . WA6CEZ, . . . . . 

Look whot's happened to them, 

220 MHz Receiver . - WB2EGZ, _ , . . 

A superregenerotive receiver for poor folks. 

Ham TV: Let*s Get Going .,,,,••,,., K3ADS 

Port I: Theory, testing and receiving. Part II next month 

The Multical K9VXL. 

A multi-purpose crystal calibrator. 

Connectors for Surplus Tubes ,.,.-*,*. K2ZEL. . • . 
Use those 2C39's and 4X150''s you got so cheap, 

DX Vertical , , _ , , W0IFY. , , , 

Very simple, very cheap, very effective. 

The Humidivox . WA2IKL, , , , 

Here's a new idea for avoiding citotions. 

Gus: Port 16 . • W4BPD. . . . 

After you read this, you'll want to move to Aldabra, 



WTW and You, Mr. DX'er W4BPD 

And the WTW Countries List- 



30 



38 



42 



48 



50 



52 



58 



60 



66 



The Future of the 10-Mefer Band . . . . • •Nelson, , , , , . 70 

It'll be coming to life in not too long. 

The WRL Duo-Bander ........ W8QUR 74 

Ralph likes it; two bands for 50^ per watt. 

The RF Discriminator K7DEP 78 

It's little-known to hams^ but very useful, 

AM vs. the Carrier .,...,..,.,,,, ,W7CSD, , . , - . 82 
Here's proof that o carrier is not affected by AM* 

Propagation • • • Nelson 88 

How do you like our new propagation charts? 

Zener Diodes ,..-...., W2DXH .,.,.. 108 

Here's on excellent article that explains zeners in detail. 
Tells you how to check and use surplus ones, too. 



De W2NSD/5Z4 .,_ 2 

Unlike CT Transformers ..... 27 
Touch Key 29 



New Products ....... ^ ., * « # 86 

Letters . ...... 90 

Coveot Emptor • 1 24 



\ 



^ 



I 



I 

1 



de 

W2NSD/1 



never iay die 



de W2NSD/5Z4 

This is being wiitten wliile on ''safari" in tlie 
remote wilds of northern Kenya. I put safari 
in quotes because tlie 1966 concept of a safari 
over here is probably quite different from any- 
thing you have in mind. It certainly is different 
from the stories I have read and movies I have 
seen down through the years of safaris. Per- 
haps I should disclaim here: readers who want 
only ham info in their ham magazine should 
turn to the next article because there is abso- 
lutely nothing of amateur radio to follow; 
Readers who have mistaken 73 for Holiday or 
Venture may be interested in the adventures of 
a newcomer to Africa- 

The trip over here from Boston was sup- 
posed to take just one day. Jim Gotten W5PYI 




Wayne with guides and waterbuck, 



and Larry Frank WA6TCI arrived on Monda 
night and I picked them up in Boston ani 
drove them up to the 73 headquarters for 
day of getting acquainted. Larry had bee 
with me in 1963 on the 73 tour of Europe 
On Tuesday we finished our packing and ha 
a long QSO with Hobby 5Z4ERR in Naiiob 
Robby answered a lot of our questions for u.* 
When we finished our QSO with Robby w 
were called by 9Q5HF in Linga in the Congt 
We are planning on visiting Ed after our safai 
and visit to Kenya. Ed assured us tliat w 
could visit the Congo in perfect safety* Tha 
was comforting* 

Jim Fisk WA6BS0/1, who is minding th 
button factory while I'm away, drove us a! 
down to the airport Tuesday evening. We ha< 
gone to lengths to make sure our baggage wa 
within the weight limit of 44 pounds ead 
providing they didn't weigh us with our han< 
luggage. Our flight was by Alitalia to Rom 
and then, with about a two hour delay, All tali 
on to Nairobi* With everything connectin; 
right we should leave Tuesday eveuiiig ani 
arrive in Nairobi the following evening. 1 
took us three days to get to Nairobi. 

The flight started off an hour late, makin; 
us a little nervous about that connection ii 
Rome. They had oversold tlie tourist compart 
ment and the three of us had to suffer throug] 
tlie ten course dinner and champagne of th 
first class section. The seats were much large 
and roomier too, but not really comfortabL 
enough to promote much sleep. We arrived th( 
next morning in Rome rather pooped. OK 
where do we find the Nairobi plane? Th 
AMtaHa people looked nervously at each othei 
Where is it? Well, you see, we er , • . ah . . 
had to cancel that flight. Today is Wednesda; 
and we think we will have another flight o] 
Saturday. Certainly by next Tuesday. In th 
meanwhile you will be the guests of Ahtalis 
You wiU stav at a nice hotel \Wth rooms am 
meals paid. 

How about alternate ways of getting t 
Nairobi? No» very sorry, but we have checker 
that and all flights are fully booked. You'd be^ 
wait for our Saturday flight Most of the peopl 
caught in this situation just gave up and wen 
to the hotel, Not us* Jim grabbed an airUn 
manual and started looking up possible way 
of getting from Rome to Nairobi . . . via any 
where. Of the many possibilities the bes 
seemed via Tel Aviv or via Alliens. We trie^ 
for reservations on these t^r^o paths and boti 
came through for us* We flipped a coin and i 
was Athens, That w^ould get us into Nairot 
by Friday noon. 

(Continued on page 96 



73 MAGAZmi 



1 

ME\A/ from In^erna'tional 



SINGLE SIDEBAND 

9mc EXCITER-DRIVER 
50-54mc MIXER-AMPLIFIER 

The SBX-9 Exciter-Driver and the SBA-50 Mixer-Amplifier 
provide the perfect combination for 50-54mc SSB operation. 
Performance, versatility and reliability are incorporated 
into this new SSB pair, A tremendous value at a low price! 




Model SBX-9 : Model SBA-50 



SPECIFICATIONS: 

Exciter-Driver 9mc 

fubesr 6BH6 Oscillator 
12AX7 Audio 

7360 Bal Modulator 

6BA6 RF Amplifier 
Filter; Four crystal half lattice 

Carrier SLrppressjon 45db min* 

Unwanted SB Atten,40db mln. 
Dutput: Provides voltage drive for 

mixer such as SBA-50 
Controls: Carrier Balance 

Microphone Gain 

Test Switch 

USB-LSB Switch 
Metering: RF output for balance 

adjust. Two sensitivity 

ranges avaitable with 

front panel switch. 

Relay included for push-to*talk 

operation. Crystals for upper 

and lower sideband included. 

Requires high impedance microphone. 

For operation on 117 vac 60 cycle power, 

$125.00 



Order direct from 
Internatiorral Crystal Mfg. Co. 



Drive: 

Output: 
Controls: 






MiSC: 




SPECIFICATIONS: 

Mixer-Amplifier 50-54mc 
Tubesi 6 USA OscilIator-Mi)cer 

12BY7A Amplifier 

6360 Linear power amplifier 

Requires 9mc sideband signal 

from SBX-9 

SSB single tone 10 watts 

On-Off Power 

PA Grid Tune 

PA Plate Tune 

PA Load Tune 

Metering Switch 
Metering: Oscillator 

9mc Drive 

Buffer Grid 

PA Grid 

RF Out 

Three positions, uses 3rd 

overtone 41-45mc range* 

Crystal frequency = final 

frequency — 9m c 

Accessory socket provided for 

connecting keying circuit to 

SBX-9, Comes with three crystals. 

Specify frequency when ordering- 

For operation on 117 vac 60 cycle power » 

$145,00 



Crystals: 



MiSC: 




INTERNATIONAL 




CRYSTAL MFQ. CO.. INC. 

1Q NO. LEE • CXLA. CITY, QKLA. ■73102 



OCTOBER 1966 



> 




Integrated Circuits 

Hoic will they affect you? 



^ 
^ 
^ 



Tiny integrated circuits are making a big 
noise in the electrouies industry* In the past 
year or so, they've fust about taken over the 
fobs once held by transistors in computers. 
Now IG's are creeping into consumer products 
like TV sets and portable radios; they may 
take them over completely in a few years. 

So what are integrated circuits? What do 
they do? How are they different from more 
familiar electnunc cnmpoiieiits? How are they 
used? And most important, how will they 
affect our hobby? 1 liope this article will give 
a short, if incomplete and oversimple, answer 
to these questions. 

What are integrated circuits? 

Integrated circuits are electronic circuits 
made from miniature electronic components 
mounted on small insulators. Some IC's have 
been around a long time. Remember the flat 
Couplates used in radios and T\^' sets? These 
small ceramic plates with resistors and capaci- 
tors printed on tliem can take the place of 
many larger individual components* Couplates 
are simple integrated ciieuits* 



IC's con offer these odvantages over con 
vetttional componetits and construction t 

Versatility 

Reliability 

Light weight 

Low power requirements 

Low cost per function 

High input impedance 

Wide frequency response 

Small size 



gotn 
Low phase shift 
Simple external circuitry 
Easy go in control 

Possible disodvantoges of IC's compared to 
conventionol circuitry: 

Parasitic capacitances between components 

Parasitic tronsistors and diodes 

Only small capacitors con be used (under 

500 pF) 
Only small resistors can be used (under 

100 k) 
Inductors can't be included in IC's 
IC resistors aren't precision 
IC resistors have high temperoture coefficient 
An individual can't design his own IC's 
"IC circuitry is different" complain some 

hams 



But the ICs lliBt are attracting so much 
attention now are ditleient from earlier ones. 
They contain not only resistors and capacitors^ 
but also diodes and transistors. These inte- 
grated circuits are of two type,s; monoUthic 
and hyhncL A monolithic IC is formed from 
a single cliip of silicon. Components and con- 
ductors are etched on its surface by clever 
photographic and chemical processes. The 
chip is moiuited on a small terminal block 
with thin wires soldered from the proper 
places on the surface of the chip to the ter- 
minals. Then the whole assembly is mounted 
in a sealed case or dipped in plastic for pro- 
tection* 

A hybrid intejiirated circuit is basic^ally a 
monolithic IC el up with small components 
made from thin films of nichrome or other 
materials mounted on its surface. These films 
can be used for components that can't be 
made from silicon^ such as liigh-value resistors. 
Another name for this type of integrated cir- 
cuit is thin film. 

Most IC*s ha\e been made from silicon^ but 
experimental ones have used other semicon- 
ductor materials. The transistors in present 
conmiercial IC's are conventional bi-polar de- 
vices, but various types of uni*polar transistors 
such as field effect trunsistors have been used. 
ICs using FET's probably will become more 
popular as th( ir prices come down, 

lt*s easy to draw the schematic of an IC 
since it's composed of more-or-less conven- 

(Contii^ued on page 120) 



OtITPUt 

Q 



INPUT O 



Q-¥ 



Th 



6- 




O INPUT 



CONSTANT CURRENT SOURCE 
(TRANSISTOR REGULATOR! 



Fig. 1. Schematic of a very simple, but typical, 
type of integrated circuit. 



73 MAGAZINE 



."V 



erish the thought Penelope . . . 



. . . simply doesn't make 

ordinary gear for extraordinary liams 



Mod. 369 






REFLECTOMETER 

J115. 



CLIPREAMP'^"' Mod. 372 . $21.95 

(less battery] 



We've long since learned that the ham using Wa- 
ters gear is a critical cuss, far femoved from the 
ordinary. His respect for quality and performance 
is deep-seated and sincere. For him to keep pace 
with advanced thinking and up-dated equipment is 
as natural as transmitting a sharp signal. You sim- 
ply don't make ordinary equipment far this kind 
of ham. Waters doesn't. 



REFLECTOMETER 

Measures both forward and reflected power 
simultaneously on unique double meter. 
Covers 3 to 30 megacycles at 52 ohms 
on two separately set forward scales of 
200 and 1000 watts. (20 and 200 watts 
reflected) to insure accurate readings. 
Comes complete with directional coupler. 



\t^t 



CLIPREAMP 

You'll get more "talk power" into your 
signal with a Clipreamp! Seff-powered and 
solid state it installs in the mike line of 
either fixed or mobile station. Takes just 
a jiffyt Great for that added punch when 
QRM and band conditions are tough. 



■ .•_.'. . ^ r. ^ ■ '.• • ■ 







Mod. 



II 






^•.: 



: ' .^■. :.-> .;.:.•; •^:4ii--- / 



CODAX^''^ AUTOMATtC KEYER $92J0 

Ubss batteries] 



CODAX "^ 

The automatic keyer that puts rhythm- 
smooth CW at your fingertips. Feather- 
touch double paddle is automatically timed 
for 5 to 50 WPM. Operates block grid or 
into mike jack for VOX CW on either side- 
band. Monitors the signal, too! 



A. 



WATERS 

MANUFACTURtNG INC. 

WAYLANO. MASSACHUSETTS 



Waters Qyality Products Are Sold Only Through Waters Oualified Distributors 



OCTOBER 1966 





' 



Ed Marriner W6BLZ 
528 Colima Street 
La Jolla, California 




Marrinero 



A Portable SSB 80 m Transceiver 



This is an 80 meter SSB transceiver for the 
man who hasn't ever\4hing. It has an input 
of about 70 watts, and is biiilt out of old 
standard radio parls^ partially because they 
are cheap. Call it a pre-historic monster if you 
wish; it works fine- Tlit^ only argument for 
building this rig is that it is a complete unit 
with tlie power supply all on one chassis, and 
it is a little cheaper than buying a one-band 
kit. It might take a little too much experience 
for the average amateur, but the old soldering 
iron artists should not have too much trouble 
with tlie straightforward eircm'ts* 

The original idea for building this trans- 
ceiver was to have something around the 
shack that could be taken on vacation trips 
without W7)rrying tluil kiiooking around would 
destroy its resale value* Tlie time spent build- 
ing tlie rig, however, left some pensive 
thunght on the future of amateur radio. Let's 
face it, gone are the days of building an os- 
cillator-amplifier rig in one afternoon, it took 
several months to turn this one out. You have 
to be a real nut U> build anything these days. 
It should not be too far in the future when all 
you have to do is go to the radio store and 



buy a transistor board all made up and just 
plug ill the parts. Why not? All of tlie circuits 
are worked out and are standard. 

There are today plenty of amateurs in all 
parts of the world who are not as lucky with 
their dollars as we in the U.S.A. Tliey are 
also tied up with import taxes and the high 
cost of radio parts, Tliey still are high up on 
the list of surplus part users, so this ardcle 
wiU be a big help for them. This rig is small 
and came out about the same size as any tran- 
sistorized rig using the equivalent power input. 
It should do tlie job for the boys overseas be- 
cause it is portable, compact, and yet cheap. 
If this proves anylhingj we might say that the 
old parts still have some good qualities, and 
ai'e still mechanically reliable, even though it 
may not be progress if that is wliat we must 
have in otn* radio magazines. 

Theory 

This SSB transceiver tunes from 3.75 to 4.0 
MHz using a VFO made with the variable 
capacitor taken out of an ARC-5 transmitter 
for vernier tuning. The input to the transmit- 
ter portion is about 70 watts PEP, and the rig 



73 MAGAZINE 



ilVC 




rg, L Block diogram of El Marrinero, a portable 
meter SSB transceiver built by W6BLZ. The 



circuit is quite simple for a sideband transceiver. 
Optional VOX is shown in Fig. 6. 



3 all self-contained with the 700 volt power 
upply all on one chassis. It uses a Collins 455 
Hz mechanical filter which can be obtained 
ty sending $26.50 to Mr. Don lacoboni. Col- 
ins Radio, 19700 San Joaquin Road, Newport 
Jeach, California. Ask for the amateur type 
liter, F-455-FB-2.1 with a 2.1 kHz band- 
vidtli. This unit is cheaper than the other 
ilters used in commerciar equipment 

Here is how the rig works: The block dia- 
gram is Fig. 1, the schematic Fig, 2, In the 
eceiving section a 80 meter signal from the 
intenna passes through a TR switch composed 
jf a 6 w^att 120 volts lamp and two diodes^ 
md is fed into the antenna coil. The tuned 
lignal is then applied to the grid of a 7360 
rdxer tube directly without any rf stage- Here 
he signal is mixed with the VFO and comes 
)ut at 455 kHz and fed into the mechanical 
liter by two relay contacts. The input and 
jutput of the filter is tuned to 455 kHz by a 
ixed 130 pF capacitor across its input and 
>utput After passing through the filter the 
signal is amplified by two stages of 6BA6 if 
implification, detected in a product detector 
md then audio ampUiied, AVC is obtained by 
ectifying voltage from the first audio tube 
md applying it to the 7360 and the tw*o if 
'ubes. It is simple and effective^ 
H In the transmit position the low frequency 
:3rystal oscillator (456.360 kHz) is applied to 
a diode ring modulator and combined with 
the audio speech. The output of this modu- 
lator is sent through the filter by relay con* 
tactSj and amplified by one stage of 6BA6 */ 



amplification. The plate voltage is applied to 
this tube at all times because it is used in both 
transmit and receive position, while the sec- 
ond if tube is only used in receive position. 
After the signal comes out from the first */ 
amplifier it is mixed with the VFO signal 
(3.3-3,555 MHz) in a 12AT7 mixer and comes 
out in the 80 meter phone band. (This include 
the Canadian portion) The five volts of rf 
produced by this mixer is enough to drive a 
6AG7 driver tube that in turn drives a 6146 
which has about 600 to 700 volts applied to 
its plate, at about 150 mA. The output signal 
is coupled to a coax 52 ohm line by tapping up 
from the giound end of die coil. This works 
satisfactorily and makes for simple tuning 




Back view looking toward the front panel. The car- 
rier balance pots were later moved to the front 
panel for operating convenience. 



DCT08ER 196$ 



■H^ 




Bottom view. The base of the 6AG7 driver is 
shown in its shielded compartment. 



compared to a pi network. A small antenna 
tuner can be made with broadcast type receiv- 
ing capacitors, or fed directly into a di-pole or 
mobile whip type of antenna. 

It should be pointed out here this rig can 
only be used on 80 meters because it is single 
conversion. The VFO being only 455 KHz 
away from the output signal would prohibit a 
tuned circuit from tuning it out on 7 MHz. It 
eoiild be done %vith more tuned circuits. More 
tuned circuits are necessary as you increase 
m frequency to accomplish the same refection. 

Construction 

This transceiver is built in a California 
Chassis cabinet LTC #470 which has included 
a chassis 5% x llKe x B% inches. Layout is 
shown in Fig. 3* Since this rig was a bread- 
board there might be a better arrangement, 
and an experienced constructor miglit find it 
desirable to re-arrange some of the parts. If 
parts are placed in other positions be sure and 
keep the 7360 as far away as possible from 
any choke or power hansformer field to pre- 
vent its being modulated, It is a good idea to 
keep the audio section shielded off from the 
diode rectifiers, and filter chokes. Diode recti- 
fiers often develop large transient signals 
which can be picked up in a high gain audio 
amplifier if it is too close. This receiver is 
absolutely clean from hum and diode switch- 
ing noise in the parts placement shown. 

The constructor might have thoughts of us- 
ing a variable capacitor to gang tune the slug 
coils for the mixer-driver-amplifier. If this is 
done good shielding will have to be used to 
prevent picking up rf causing oscillations. 



Keep even the slug coils small. Using fixe 
250 pF mica capacitors across the coils 
tuning range across the 80 meter phone ban 
is satisfactory without too much falling oS ( 
drive without re-adjustment of the slugs* 

One of the main feature of this transceivt 
is that tlie power supply is mounted on th 
chassis. More space could be saved if a tran: 
former could have been obtained witli a hu 
winding, but this transformer only cost $2.9: 
and it has a filament 6,3 volts at 9 A, and th 
secondary handles 210 mA. 

Construction was started by mounting th 
power supidy in one ct)rner of the chassis an 
wiring it so that the available voltage coul 
be used to check out the circuits as they wer 
completed* 

Next in line was building the VFO and tlie 
finishing the recei\'er portion. Nothing wa 
finished until the receiver was operating, an^ 
then crnistruction was continued on the tranj 
mitter section. 

Low frequency crystal oscillator 

Since most amateur operation on 80 raetet 
SSB is on the lower sideband, and becaus 
crystals are expensive, only the 456.360 kH 
crystal was used. This cr\'stLLl can be obtainei 
by wTiting to Mr. P. M. Freeland, Internd 
tional Crystal Co., 18 North Lee strrt I Okla 
homa City, Okla. and asking for the specie 
amateur crystal for this frequency in a F-60 
holder. It will cost about $8.00. If this is toi 
much the other solution is to buy a 50 cen 
surplus cr)stal marked Channel 46 and edg 
sand it down to the proper frequency. Some 
times by buying a number of these surplu 
crystals, one will be found that is good 
enough, or far enough down on the slope o 
the filter that it will sound okav. The crv^stal 
are spot welded to the crystal with sma] 
wires, but if a holder is made with a clothes 
pin and held carefully the edge can be sandei 
on sandpaper enough to increase the fre 
quency. These crystals are more sluggish li 
make oscillate and a 60 mH rfc may have V 
be used in the grid of tlie 6BH6 oscillato 
rather than the 2.5 mH shown. It is a goo< 
idea to use the 6BII6 as some tubes just don' 
work. Many oscillator circuits were tried an( 
this particular circuit gave tlie most output 
At first the 30 pF capacitor was not used fron 
the grid to ground but the oscillator did no 
come on ever>' time. Various values were triec 
and the 30 pF seemed to be the best compro 
mise. The crystal oscillator pxits out 15 volt 
of rf and it was found that 6-9 volts wer* 
necessaiy for the product detector. If les 
voltage is applied to tlie detector loud signal; 
do not mix. The cathode follower was needec 



8 



73 MAGAZINI 




vertical 1 that's 



known for the 

contacts 




makes. 












.i" 




am 






* ISi *IhI^ "'■*.*? 



Model 14AVQ for 40 thrii 10 meters 

Ask any Ham who owns one -..his log will verify that for 
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vertical that can match the performance of the Hy-Gain 
Model 14AVQ. It takes maximum legal power.,. high level 
AM, SSB, RTTY or any other mode desired. It develops an 
extremely low angle radiation pattern that insures un- 
compromised performance for short haul, long haul or DX 
communications. ..on Phone or CW, Its three large dia* 
meter ''Hy-Q*' traps are individually precision toned to 
frequency to provide true 1/4 wave resonance on each 
band. And, the entire antenna is at DC ground thus reduc- 
ing atmospheric noise to an absolute minimum while 
providing positive lightning protection. Rugged heavy 
gauge aluminum construction ... easy to install on ground 
or rooftop. 

For 40 thru 10 meter operation, don't settle for less than 
the best. Get the vertical that's known for the contacts 
it raakes^Hy^Gain Model 14AVQ,„$32.5Q Net 

Roof Mounting Kit for Model 14 A VQ — Includes adjust- 
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Available now from your 
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8551 N*E, Highway 6 ^ Lincoln. Nebraska 68501 



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for 80 thru 10 meters. The 
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trap vertical Four indivfdually 
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r; i'V ' '' 






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3 
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a 



*§o« 



10 



73 MAGAZrNE 



Fig. 2. (Opposite page). Schematic of El Marrinero, 
\ ,01mF capacitor tetween the 20O£2 carrier bal- 
ance pot end the cathode follower. 

« 

because botli signals cmild not be taken from 
tlie same point because of the by-passing ef- 
fect of the .01 M^F in the ring modulator* It 
fust shunted the signal on the detector to too 
weak an outi^ut. The sohition of taking the 
product detector from the oscillator plate and 
varying the coupling capacitor (50 pF) value 
to the product detector, a 6-9 volt rf signal 
could he set. The 100 kU resistor oti the grid 
of the cathode fnllnvver does not load die os- 
cillator down and the signal for Uie modulator 
can now be taken off from the 3.3 kO cathode 
resistor which is now a low impedance point. 
This better matches the diode modulator and 
we have 5 volts here to apply to the arm of 
the balance potentiometer. 

While we are talking about the ring modu- 
lator it could be mentioned some of tlie earlv 
photographs of the rig showed the balance 
pot above the chassis on a bracket* It was 
later moved to a i^anel control, which in con- 
junction with a pF trimmer capacitor nulls 
out the carrier. The pF bakmces out the fixed 
30 pF added on the other side of the modu- 
lator to obtain a greater nulL This is necessary 
because the pot has a metal cover and being 
bolted to die chassis has unbalanced capaci- 
tance. It was foimd un- necessary to use the 
txtm capacitors if the pot was insiilated from 
the chassis. 

The vfo 

Because of the high value of shunting ca- 
pacitance across a small inductance this oscil- 
lator is mechanically and frequency stable. To 
me it is amazing having built many Unpe of 
oscillators that seemed to drift forever. Theory 
is probably nn-necessary since the 180 pF 
variable capacitor from the ARC-5 transmitter 
padded with a 50 pF .\PC t>^pe capacitor, and 
12 turns of #20 en, wire wound on a % inch 
ceramic form just tunes the 3.75 to 4*0 MHz 
amateur phone band. The oscillator itself of 
ctjurse is timing 3345 to 3555 kHz* 

A cathode follower was used after the VFO 
to prevent any pulling efi^ect on the oscillator 
which might or might not occur. If the VFO 
was just used in a receiver the follower would 
not be needed. It might seem strange that a 
9002 tube w as used for the oscillator in place 
of the 6C4, Either one will u ork, but the 9002 
is smaller and could be fitted between the box 
and transformer with no room to spare* 

No measurements have been made on the 
oscillator stability, but from a cold start it does 
not drift off from a SSB signal It has been 




VFO box. Note the coil wound on the ceramic form, 

used in several receivers with excellent results 
without any temperature compensating. 

Receiver 

Pages have been writen in QST on the 
merits of using the 7360 tubes as a front end 
and mixer because of its low inter-modulation. 
We used it to do away with an rf stage. It w^is 
found tlie giid coil should be an air uDund 
large coil if possible for the best selectivity. 
The 4.5 MHz sound if cans were tried and 
found too broad* Because of room restrictions a 
compromise was used by winding 28 turns of 
#28 wire on a XR-50 coil form with ten turns 
on the bottom for the antenna. It works half 
w^ay between the two otlier coils and is satis- 
factory. During the experiments with this tube 
several rules must be followed, tlie supply must 
be set at 200 volts by adjusting the 10 kQ 2 
watt value of resistor. Otherwise the 1200 ohm 
cathode resistor value might have to be 
changed. In some instances the plate load 
resistors have to be lowered to 27 kQ and the 
cathode resistor varied for best output mixed 
signal if a lot of output is desired. The cathode 
value can go as low as 600 ohms. When build- 
ing this mixer observe that the accellerator 
has 175 volts on it, the two plates 150 volts 
and 2 to 4 volts of rf from the VFO to swing 
the beam. If these tolerances are held there 
should be no iDroblem. AVC can be put on the 
tube after the receiver is finished and for pre- 
liminary adjustment the AVC bus can be taken 
olf and the 100 pF coupling capacitor left out 
if desired. There seems to be some advantage 
in using AVC on this tube where strong local 
signals are heard. 

The signal from the 7360 mixer is fed into 
the mechanical filter which is tuned by a 130 
pF capacitor. Whether this value applies to all 



OCTOBER 1966 



IT 



mB 



h 






■* 






PLATE 
COIL- 

eA@7 



6r46 
GRID 





ANT. 



£1 



TANK 
COIL 



ZENER 



® © 



® 




hi 
O 



lil I 

I IfL ■ 

' _« ' 

i O I 

I 111 I 

I S * 







naAUTj 



fxTAL 



RELAY TUBE 
Mm VFO CJv 






POWER TRANSFORMER 
4" X 4* 





T360 
tMlXERj 





05C. TUBE 



VFO eOX 

3"X44" 



too A 
FILTER 



Fig, 3. Layout of El Mar- 
rinero as built by Ed 
Marriner W6BLZ, 



n" 



Collins filters is unknown but should be very 
close to a practical value* This one was found 
by putting a variable capacitor across the filter 
and tuning it for resonance and measuring the 
value. 

If stages 455 kHz 

When tlie signal comes out of the filter it 
goes into a 6BA6 if stage* Here is where most 
constructors run into trouble trying to prevent 
the stage from oscilluting. In anticipation the 
cathode resistor w^as increased from its normal 
value of 68 ohms to 120 or 220 ohms and it 
is suggested that the new J, W, Miller 913-C.T, 
transformers be used. The grid tap on these 
has been placed one-third of the way down 




Finol amplifier, tank coil and TR switch, 



from tlie top of the coil to lower tibe grid 
impedance. You will notice that the coupling 
to the second if is taken off from the primary 
of thu fiist if transformer by a ,003 iiF capaci- 
tor. Smile if you will, but it serves two pur- 
poses, it allows Uie mixer grid to return to 
ground and it gives more gain phis it stops 
oscillations. This coil incidentally was modified 
by squeezing the coils to within one-half inch 
of each other. This can be tricky but by 
scraping tlie glue from the rod and insertitig a 
spacer one-half inch thick the eoil can be 
pushed up against it by taking a piece of wood 
and drill a half inch hole in it and slipping it 
over the rod. If this is not done the pi will pusli 
out or the coils will two-block and won't come 
apart (voice of experience!) It is necessary to 
push the coils togcllier to obtain enough cou- 
pling to the 12AT7 mixer giid. T]w coupling 
I rum the primary to the second if does not 
effect the selectivity because we are using a 
meclumical filter- 
Since the placement of the coils in this trans- 
c^eiver layout were six inches apart a piece of 
RG-174 was used to bring the signal from the 
.005 to the grid of the second if tube. This 
extra capacitance was too much for the 100 
pF timing the first if can and 80 pF had to be 
put inside the can in place of the 100 pF. 
The second // can tuned without modification. 

Product detector 

This product detector is becoming very 



12 



71 MAGAZINE 




PACKAGE 



I 



^ 




I 



^1 SB-34 . , . advanced Space 



age circuits. Sinall size 
solves space problems at home or 
mobile , . . only S3IS (1?V DC & 11TV 
AC built-in power supply I Write for 
complete brochure. 



^AYTHEOiy 



213 E^ Grand Ave 
So. Sai) Francisco, Ciitif, 94OS0 



OCTOBER 1966 



n 



RF PfiOBE: 



SOpF 



IN34A 




TQ DC INPUT ON 

HEATHKIT VTVM 



THIS CAM BE eUJLT INTO A METAL TUBE SHIELD, 
UStNS A 9*PIK SOCKET 

Fig. 4* RF probe for tuning up El Marrinero. 

popular as it saves a tube. Just don't use silicon 
diodes or it won't work, there has to be in- 
ternal leakage. The original circuit used IN67*s 
but lN298's and lN38's Ihave been used. The 
RFC keeps the rf from getting into the audio 
which might cause hissing. A 47 kQ resistor 
works just about as well as the RFC, 

This completes the receiver. To ahgn it it 
would be nice to have a signal generator or a 
455 kHz crystal, however^ if you don't just 
tune in an 80 meter signal and peak the if cans 
for maximum output Remember to ground the 
AVC bus before tuning. 

The rectified audio used for the AVC will 
go up to 15 volts on loud signals. The length 
of time it holds up can be varied by changing 
the value of the 2.2 MQ resistor and the 0,6 
uF Mylar or low loss capacitor. The hold-up 
time can be watched on a VTVM voltmeter. 

With an rf probe make sure tliat at the 
junction of the two diodes of the product de- 
tector have 6 to 9 volts, if there is not enough 
voltage such as 2 volts, the signals will sound 
distorted or not mixing. This can be very 
apparent if you just pull the crystal out i£ 
you care to see what it sounds like with no 
injection. 

It might be mentioned that tlie screen of the 
6CX8 must be by-passed with a heavy capaci- 
tor such as the 4 iiF to obtain increased gain. 
With tliis by pass no capacitor is necessary on 
tlie cathode. The screen voltage is held con- 
stant by the 33 kQ resistor voltage divider, 
making this tube different from using a 6AQ5 
where it is not necessary. 




22 VDC 



Fig. 5, 1200-Hz tone oscilfator for inserting a sig- 
nal into the microphone jack to produce a signal 
for tuning. Construction isn't criticat. 



Confidentially this is a pretty good receiver, 
simple and easy to build except for taming 
oscillations in the ifs. 

Test equipment 

There is no limit on the amount of test 
equipment that could be used when building 
SSB equipment. Many look with awe or 
askance w^ien I say this rig was built with 
just a grid-dip meter, Heathkit VTVM and 
an rf probe and a b or routed RCA signal gen- 
erator which had a variable output so that 
initial voltage injections could be found, A 
similar rig was built without the generator and 
only a 200-500 kHz receiver used to listen 
to the signal at 455 kHz before it was mixed* 
Most of the SSB trouble come from mixing 
or oscillations in the 3.8 to 4.0 MHz region 
of the driver or final amplifier tubes. A re- 
ceiver in the 3-40 MHz frequency range would 
naturally be helpful listening to the VFO and 
the final signal but you could get by with 
just a GDO. Once the 80 meter signals are 
picked up you can use them to test and align 
the rig. The test gear ranges then from nothing 
to as much as you can lay your hands on. The 
more you fuss with building the gear, the less 
test equipment you need and more ways can 
be fovmd to improvise . for any particular ad- 
justment. I find a calibrated capacitor handy 
w^hen trying to find out w^hat value of fixed 
capacitor to put across a coiL A GDO is handy 
for finding a coil's resonance. A field sh^ength 
meter is handy to balance out the carrier, or 
when tuning up into a dummy load. The old 
'"Q" fiver tuning 200 to 500 kHz is nice to 
listen for the first squeek of life out of the 
6BA6 if amplifier. At least you know you are 
SSB on 455 kHz. An rf probe is a necessity; 
see Fig. 4* 

Transmitter portion 

Here we are at the transmitter portion. 
When we are through with this article you 
have had a course in SSB transciever con- 
struction. 

Many circuits were hied before ending up 
with this present configuration. Each time tlie 
rig was finished something new appeared to 
cause circuit changes. Originally a 7360 was 
used for the balanced modulator. It seemed to 
work fine most of the time, however, every 
once in a while carrier would appear. The 
trouble was traced to changing accelerator 
voltage, which caused upbalancing of the car- 
rier. The tube being in the field of the choke 
also caused carrier unbalance as the field 
around the tube changed. The circuit was 
changed to the more stable diode ring modu- 
lator. 



14 



73 MAGAZINi 



The circmt has been described up to 
he 12AT7 mixer where we squished the 1/ 
•oil together to drive the grid of the mLxer, 
7he VFO signal was picked up by a field 
trength meter in the mixer output coil. The 
mall capacitor between its plates was varied 
intil the signal from the VFO was reduced 
nd the coil tuned up by feeding a tone into 
he audio input of the transmitter. The output 
if the mixer should be about 5 volts of rf 
o drive the 6AG7 which builds the signal up 
o 30 volts of rf sufficient to drive the 6146 in 
tB-1. A shield box was put around the 6AG7 
ocket and a shield across between the grid 
nd plate pins to prevent oscillation. The sig- 
tal was carried to the 6AG7 grid by RG-174 
oax. The output signal to the 6146 grid comes 
hrough the box by a feed-through insulator, 
Jsing this shielding techtiique the 6146 did 
lot need neutralizing. Since the grid circuit of 
he 6146 is tuned and coupled to the tank coil 
if the 6AG7 inductively to prevent \nFO feed- 
hrough, it is prone to self-oscillatioa unless 
extreme shielding is used. If tuning capacitors 
md large coils are used tliey should be put 
n a box* For AB-1 operation the 6146 needs 
ibout 50 volts of bias. The 6AG7 bias is ad- 
us ted for —10.5 volts so that the cathode can 
)e grounded. This tends to make a more stable 
hiver tube arrangement 

Tuning of the transmitter can be accom- 
ilished by inserting an audio tone into the 
microphone input (See Fig. 5 for a generator) 
?r by unbalancing the carrier control knob 

dightly. 
If you*d like to include VOX, the circuit 

-Qv it is shown in Fig. 6. 

Well, thats it, Im proud of my little rig that 
loes witli me on vacation trips. Despite the 
struggle getting all of the bugs out of it I had 
run finding out for myself how the various 
5SB circuits work rather than just reading the 
Mok, Tm sure there are many improvements 
hat could be made but the rig sounds first 
-lass, and that is what counts. 



1/2 EAt/T 



1/2 IZAU7 



HD PLATE OF 




TOP-MAT OiD<)€SllN2404jM538»ETCj 



f ADJUST TO aXJSC f»^AY 






I 



*fZ40 



Fifl. 6. Optional VOX circuit for E! Marrinero. 



MASTER MOBILE'S NEW 




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FOLD-OVER ANTENNA & COILS 



'^ it > 



1 



10^15-20-40-80 
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Extension lays over at 18". Extensfon, 
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Constructed of stain less steel with brass 
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EXT. 
AM -29 



COIL AND 

WHIP 



BANDWIDTH RESONANT FREQUENCY 
10 Meters — Approx. 100 to 120 KC 
15 Meters — Approx. 100 to 120 KC 
20 Meters — Approx. 
40 Meters — Approx. 
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40 to 50 KC 
30 KC 



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DEPT. 73 




OCTOBER 19(6 



Bob He J I K9EID 
Holiday Inn East 
Columbus, Ohio 



Two Tubes for Two 

Get on ttvo meter sideband with only two tubes 
(and a W-nieter SSB transiniUer^ of course). 



With the increase in activity and the tre- 
mendous amount of nighlly QRM on the lower 
frequeBcy bands, we are all forced to move 
up in the spectrum in order to enjoy our op- 
erations. Until now, most of the transmitting 
converters to allow lower frequency SSB units 
be used on VHF have been so complicated, 
that the converter costs more than the SSB 
generator! Here's a unit that wall let any 20 
meter SSB transmitter be used on two meters 
with a minimum of materials^ time, and labor. 
Tlie end result is most satisfving and will give 
you liours of pleasure witliout that darn QRM 
and lower frequency squabble! 

The ''Two for Two" consists of a simple 
6EAS oscillator generating 43,333 MHz in the 
triode section and multiplying that up to 130 
MHz wliich is fed into the cathode of the 
6360 mixer, A 14 MHz signal from the exciter 
is fed into the grids of the 6360 with a pre- 
womid 20 meter coih This makes a very easy 
coil-winding job to construct the Two for Two, 
The coupling link in the coil can be moved to 
allow proper coupling for the amount of in- 
jection needed to drive the 6360 mLver-finah 

The power supply can be built on a sepa- 
rate chassis, or on the back of tlie converter 
chassis, depending on the method and space 
of using the Two for Two* The reason for this 
is that you ]ust may have room in your existing 
lower frequency transmitter to allow the 
mounting of the Two for Two on the back 
panel or on a lip inside the top cover. The 
power supply w^ould thea be remote* In any 
event the power supply is ver>^ simple, I used 
an old discarded television transformer and de- 
signed the supply to give me all of the voltages 
needed, including tliat always troublesome bias 
voltage* So many of tlie bias voltages in equip- 
ment built today have the battery supplies that 
always cai^e trouble wdtli dead batteries and 
consequent loss of tubes- This one is a very 
simple, but yet tremendously effective supply 



that allows complete cut-oflF of the final during 
the receive periods via SL 

Construction of the unit is very simple and 
straightforward. The only item to watch dur- 
ing construction and layout is that you mount 
the 20 meter B & W input coil, L3 on top 
of the chassis and the final amplifier coil, L4 
underneath in order to allow complete shield- 
ing between the input and output sections. 
This also aUows for the output meter to be 
mounted on the front lip of the chassis along 
with the plate and load controls of the final* 
The grid capacitor, CI is mounted on the back 
portion of the chassis with the shaft extending 
dirough the bottom of the chassis. Tliis con- 
trol need only be set once and forgotten^ as 
any peaking of this section can be done with 
the exciter. If you desire to mount the con- 
verter in your present transmitter, merely build 
the rf section* This will make a small strip of 
chassis to mount inside the cabinet. The power 
supply is built on a separate chassis and re- 
mo ted, SI, the bias control, is most conven- 
ient as part of the antenna coasdal relay. This 
can be wired to work wdtli your SSB trans- 
mitter therefore maWng complete control of 
the two meter station just as it is on 20 meters, 
VOX and alll 

The crystal socket can be mounted by sol- 
dering the pins of the socket directly to pin 
nine of tlie 6AE8 and a ground lug. LI is 
mounted as close as possible to pin one as L2 
is to pin six. This allows for the link from L2 
to lay close to pin t\\ o of V2, 6360. Both rotor 
sections of CI are connected directly to the 
coil, L3, all above die chassis. Two small 
grommets are mounted at each end of L3 in 
tlie top of the chassis and the 10 ohm resistors 
are wired from pins one and tluce up through 
the chassis to L3, The two 470 ohm resistors 
are mounted directly on the coil form, L3, as 
the bias center tap is fed through another small 
grommet to the power supply station, C2 is 



16 



73 MAGAZfNE 




6560 




144 MKl CSUT 




0-tOO 



L005 5h 



K^ 



/r^ 



L4-t4 TURNS Na£2 ENAM 014 1/2' 
SLUG-TUNED FORM 

L2-7 TUWe N&.ZO E^iAM ON 1/4* SUU^-tUNCO 
FDfM. WITH 2 TURN LMK 

L3-BftW 25 W Plug- IN TYPt COIL ASSEMBLY 

L4 - 5 TURNS Bft W hK>. 3002, C*T*. WITH Z TURN UNK 




I 



Fig. 1 . K9EID's Two for Two two meter sideband 
mixer- This simple circuit converts 20 meter side- 



mounted on the front panel so that the stator 
sections a^in actually slip right into the pins 
six and eiglrt of the 6360 tube socket. Solder 
these connections and then solder tlie coil 
form, L4 directly to the pins six and eight, 
also, C3 is mounted directly to the right of C2. 
All of the rf output meter components are 
mounted on the front panel. Be certain to ob- 
serve the shunted resistor across the rf choke 
^n the plate lead of the 6360. This is installed 
^to prevent any self -oscillation of tlie rf choke 
p^d the final capacitor. 

i Upon completion of the construction, which 
l^ould take only one good evening of your 
time, begin tune-up by first measuring the 
plate leads with all power oflF with a VT\*M 
to check for any shorts or misconnections* 
-After this is determined, apply filament volt- 
pige and wait for warm up. First measure the 
bias voltage at pin one or three of the 6360, 
SI should be open^ or in the receive position. 
The voltage here should read around —50 
volts. Close SI and while continuing to read 
this bias voltage, adjust Rl so that the bias 
reads about —22 volts. Now observe the color 
of the 6360 plates. Tliey should not be red. 
li they are, adjust Rl until they show no 
trace of color; further checking \\i\\ likely re- 
veal that the plate and screen voltages are too 
high as a result of differences in the power 
supply components. Adjust the resistances so 




%tm 



1 



6360 
5 



bond energy to 144 MHz, ft can be used alone for 
Q few watts of SSB, or with on amplifier, 

that the plate of the 6360 reads +280 to 300 
volts and the screen +160 to 180 volts. 

At this time it will l)e necessaiy to begin 
checking the oscillator witii the grid dipper 
for tiniput. Adjust LI for maximum 43.333 
MHz energy. Then adjust L2 for maximum 
130 MHz energy. Wliile using tlie dipper, ad- 
just L4 and C2 to resonate at 144 MHz. No\v 
apply 20 meter energ>^ from the exciter and 
tune the plale and load control of the exciter. 
Adjust CI for maximum grid drive to tlie 6360. 
The last adjustment will be to adjust the plate 
and load of the 6360 to your antenna system 
and set R2, meter shunt for mid scale reading 
with full carrier injected from the exciter. 
Don't forget that SI must be in the transmit 
position in order to have any energy pass 
through the mixer and final of the Two for 
Two. The tube is completely cut off in the re- 
ceiver mode. 

This should complete your unit. A linear 
amplifier can be added for higher power, but 
is not needed for most two meter SSB com- 
munications. This unit nms a few watts PEP. 
With a fairly decent antenna system this signal 
can have the effectiveness of much higher 
power and will do quite nicely for those night- 
ly contacts without all the muss and fuss, 
though you may need an amplifier with more 
tuned circuits if vou have any TVI. Have fun! 

. . • K9EID/8 



OCTOBER 1966 



17 




" — . ji^M^mM. 



A Practical 432 




1 



Top view of the 432 MHz 
mixer (top) ond local in- 
jection generator. 



Del Crowell K6RIL 
1674 Morgan Street 
Mountain View, CoL 
Photos; Ken Hetchler 



Transmitting Converter 



This easy-to-buUd and not-too-expensive converter 
will put your 1 meter SSB^ AM or CW transmitter on 70 cm* 



€J6 
50.5MMt \tZOpF lOrMKjT 



6J€ 




TO REC 
CONV. 



®T0 XM\T 
t.SWOUTt 



O+I50 tTOmft) 



O 6.3V 



•ij^.Oft 4lURIfS M0.22 !/©"!,(?, 



Fig, K Schemotic of the local oscillotor and multi- 
pliers for K6RIL's transmitting converter for 432 



MHz- It puts out about a half watt on 404 MHz 
for local iniection for the mixer* 



18 



71 MAGAZINE 



MATERIAL IS .032 BRASS - HOLE StZ€S TO BE DETERMINED FROM PARTS US€D 
B-UZ"- 



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COVER 



TOP 



TOP VIEW 



END VIEW 



^P Fig. 2, Loyout and construction of the local 

Like to get on 432 MHz? Aetivit>^ on the 
band is increasing evety day, and the con- 
verter described in this article makes it 
possible for many hams to increase theii" fre- 
quency coverage and modes of transmission. 
This trausniitting converter can be built at 
reasonable cost for operation on 432 MHz 
using CW, SSB, or AM, This is a linear sys- 
tem which reproduces the type of signal that 
is fed into it The input frequency of 28 
MHz was picked to reduce spurious signals 
and be compatible with most 10 meter trans- 
mitters. It will work with simple transmitters 
designed for only CW and AM, or with more 
elaborate units that cover all modes of trans- 
mission. The construction follows in two parts. 
The transmitting converter and local oscillator 
chain are built as separate units to allow 
versatility, and for easier installation into 
chassis with higher power amplifiers. 

Local oscillator chain 

Tliis oscillator and multiplier chain shown 
in Figs. 1 and 2 uses inexpensive tubes. It 
starts with one half of a 6J6 as a 50.5 MHz 
DSciUator. It operates at low plate voltage 
with an OB 2 regulator for frequency stabihty. 
The three frequency doublers are nearly iden- 



oscillator-multiplier shown in Fig, 1* Vz size, 

tical with exception of tlie tank circuits* 

Last in the chain is a 6J4 grounded grid 
amplifier which delivers ,5 watt at 404 MHz, 
This chain requires plus 150 V but can be 
used with plus 200 V and the output power 
will be approximatel) 1 watt- Good con- 
struction practice must be used as in most 
UHF circuits: direct connections, shielding, 
short leads, good b\passing, etc. 

By building the oscillator and multipHer on 
a separate chassis the builder can use it for 
other experimental work. The unit is fixed 
frequency- It can be mounted in any position 
as it doesn*t require constant adjustment. 

Variable capacitors used are JFD but any 
good quality piston capacitor can be sub- 
stituted, The largest expense is feed-through 
capacitors* These can be any coaxial type, 
threaded or solder-in, which are used in TV 
UHF tuners. These are easily broken, so use 
care in soldering them. 

Since the local oscillator chain will be 
needed for adjusting the transmitting con- 
verter I recommend that you build it first. 

The transmitting converter 

The converter is shown in Figs. 3 and 4- The 
balanced mLxer uses a 6J6 with tlie 404 AIHz 




/ 



_ocqI oscillator ond multipliers shown Fn Figs_ 1 
Dnd 2, The crystal is ot left ond output is at the 
1ght, Notice that two output links are shown. The 



6 



tI 1 VU ' 9^ ^ \ 



larger Is for the tronsiTirttfng converter and the 
smaller is for the receiving converter. The chossis 
Is made of brass« 



)CT08£R 1966 



19 






^i'i:»U 




432 MHz transmitting converter. The left com- 
partment is the input from the local oscillator and 
the 28 MHz exciter. The two center compartments 

local oscillator signal injected at the grids 
and up to 1 watt of 28 MHz signal injected 
into the cathode. 

The driver stage uses a type 5656 tube 
operating class A with -3 to -4 volts fixed 
bias. This tube has an internal screen bypass 
capacitor of 15 pF and doesn't require ex- 
tenial bypassing, The circuit is push-pull 
delivering about 2 watts at 432 MHss. This 
tube was built by Raytheon for use as class 
A and C amplifiers in UHF equipment for 
military and commercial aircraft. It is avail- 



MrXER 



DRIVER 



are mixer plate and driver grid and driver plate 
and final grid. The output connector for about 5 
watts at 432 MHz is at right. 

able through MARS or surplus outlets. Speci- 
fications can be found in ARRL Handbooks 
prior to 1955* The circuit could be rewired 
for a 6939 driver with good results. 

A 6939 in the output stage does a fine job 
as a linear amplifier operating class AB2 with 
fixed bias of -6 to -8 volts, Plate current varies 
from 35 mA with no signal to 90 mA with 
full drive. It will deliver up to 5 watts output 
All stages in the tiansmitting converter are 
operated as push-pull circuits. The tank coils 
are balanced quarter waves with the ex- 

6939 
MAP 



OJTPUT 
432 MHi 
4W PEAK 




6.3V 5W PEAK 



NOTES 

•*eiiTTeRFLY 

♦ Jl^tOR 5 TURNS NO, £6 Ely AM. I /S* 



-3T0 4V 
BIAS 



TOBV 
BIAS 



+ ISO +200 

TO 200V TO 250V 

t€OmA (100 rn A 
MAX] hlAX) 



-3V 



-TV 



■VSAr 



.0. 



I 
I 
1 lOk 

I 



lOQtt 









eiAS DRCUIT 



f 

r 

i 
I 

I 



Fig. 3. Schematic of the mixer and linear ampli- 
fiers for K6RIL's transmitting converter. L6 should 



be shown as series- tuned half-wove lines with C6 at 
the end. See the photograph at the top of the page. 



20 



73 MAGAZINE 



UATERIAL IS .032 BRASS 



HOLE SIZES TO 



DETERMNTD FROM PARTS USED 



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ALL COILS MADE WTm NO. 14 OR 16 
TINNED OR SJLVCH *iRE 

BEND IWTO SHAPES SHOWN AT RIGHT 



TOP VIEW 




TYPICAL COi_ 
PLACEMENT 




CUT OUT 
SH£LDS 



COIL 


A 


B 


c 


LI 


Z/^" 


1/4" 


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3/4" 


9/(6" 


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L4 
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SIDE VIEW 



ENO VCW 



Fig. 4. Layout, construction and coil data for the transmitting mixer shown in Fig. 3. V^ size. 



are Johnson 
is soldered 



ception of the 6939 grid which uses half 
wave lines because of the high input capaci- 
tance. A quarter wave circuit would be too 
short to allow proper coupling. All lines are 
bent into a hair-pin shape. Most are bent at 
an angle as shown to conserve space and 
allow ctiupling between stages- 

The butterfly capacitors used 
J 60- 104 (9M11) and the tank 
along each side. 

Construction 

Shields are used across tube sockets for 
isolation and stability. The chassis parts were 
made from .035 incli brass^ bent to foiin the 
shape requijed. Other shapes and styles may 
be used but the constructor must keep in 
mind that shielding and short lengths are 
necessary for good performance. All voltages 
are applied to tubes by feed -through capa- 
vCitors and the dc circuitry is outside the 
chassis. Grounded tube pins are soldered di* 
rectly to the chassis and shields are also 
soldered across the sockets. Brass gives the 
builder an opportunity to solder parts directly 
to the chassis as well as to conduct heat from 
tubes • 

Adjustment and operation 

After construction is completed, check for 
errors (weiring and assembly). A grid dip meter 
should be used to adjust the timed circuits 
to frequency, 

|i Next the dc voltages and local oscillator 
injection can be applied- Dont forget the 
bias for the tubes first. The transmitting con- 
verter current drain should be under 70 mA 
total with no 28 MHz drive. Feed in 28 
MHz energ\' and adjust all the tank circuits 



for peak output at 432 MHz, Coupling is 
adjusted by beuding tlie lines for maximum 
mitput and at the same time decreasing the 28 
MHz level. After the circuits are all peaked, 
the output power should be greater than 4 
watts with full 28 MHz drive. Both the 5656 
and 6939 should indicate grid current. With 
the output c^onnected to an antenna through 
a relay, and a receivdng converter on, a small 
amount of noise will be noticed from the 
tubes which can be eliminated by switcliing 
the bias voltage to -22 volts for standby as 
shown in circuit diagram. This changes the 
bias voltage to cut both tubes oflF during 
standby and can be done by a pair of con- 
tacts on the antenna relay* 

The exciter output po\ver must be reduced 
to approximately .5 to 1 watt for driving the 
mixer input. There are many ways to ac- 
complish tliis- Fig. 5 shows the most ct)m- 
mon method. 

This conv^erter was constructed to allow 
mounting whicli \\ ill have provision for tuning 
from a front panel, I notice much of the 
equipment in magazines is without front panel 
controls. T prefer controls on all the equipment 
used at this station, as this makes for more 
flexible operation and ever\ thing can be 
located in racks* 

Good luck. See \ou on 432 side baud. 




50 n LOAD MAT BE ANT DUMMV 
LOAD WHICH WILL DISSIPATE 
(»OWER FROM TRANSMITTER 
USED. THE HEATH CANTENNA 
W0RK5 VERT WELL. 



Fig. 5, Pad tor reducing the power from a 28 MHz 
transmitter to about ] W. 



OCTOBER 1966 



21 




^ 



Robert Friess K6HM0 
2434 Rock Street #10 
Mountain View, California 





mlT^ , ^^-=-^- , 



J 



A Low-Cost FET 
Two Meter Converter 



This converter uses inexpenswe field effect tran- 
sistors as mixer rf amplifiers. It has a noise figure 
of less than 2.5 dB and very low cross modulation. 



In the last year or two several bipolar tran- 
sistors (conventional junction transistors) have 
been introduced which provide excellent VHF 
characteristics. A low noise VHF converter us- 
ing these devices will be lower in cost, pro- 
vide better performance, and use simpler cir- 
cuits than a vacuum tube converter. Bipolar 
transistors costing? onlv a dollar or two will 
produce noise figures as low as dB at 144 
MHz* Tliese devices share one serious short- 
coming, however. They are very susceptible to 
cross modulation. 

Cross modulation 

One feature that all bipolar transistors and 
diodes have in common is a transfer function 
in which the cuirent flow in a forward biased 
pn junction, e.g. the base-emitter junction of 
a tFansistor, is proportional to e*^'^*^*, where q 
is &e charge on an electron, k Is Boltzmann's 
constant, v Uie applied vcjltagc, and t the 
Absolute temperature* e^^'^^^* can be expanded 
into a series as 




+ 



eUT/kt = 1 + qv/kt + (qv/kt)- + 

2! 3! 

The even order terms produce haiTnonics, 
even order combiuatiun (re(iuencies, aiul dc 
terms. These products are usually not trouble- 
some. It is tlie odd order tenns which cause 
cross modulation. 



At room temper attire, 290^ A, kt/q is equal 
to 26 milhvolts. For voltages v greater than 
26 mV the exponent qv/kt has a value greater 
than unity^ it can be seen that the third order 
term increases rapidly when qv/kt is greater 
than unity. If v is composed of two voltages 
E^sin^jj|t + EijSinciJst a little algebra will show 
that there will be a component at t^i with am- 
plitude proportional to E,^ and a componenl 
at ^2 with amplitude proportional to E^. This 
causes cross modulation, 

TliL' action of the fiftli and higher order odd 
terms is similar to that of the tliird order term, 

Therefore^ we can conclude that wdth bi- 
pt>lar semiconductors applied voltages around 
26 mV, will result in serious cross modulation. 
It is important to note cross modulation can 
occur not only in the first stage of a receiv er, 
but in any stage where two or more large am- 
plitude signals are present. 

The designer of a receiver front end is faced 
with a serious problem, A highly selective 
filter wliich would prevent all but one signal 
from reaching a transistor or diode will be a 
lossy device. In order to have a noise figure as 
U>w as possible it is desirable to precede this 
filter with enough gain to make its eflfect on 
noise figure negligible. However, this gain may 
result in the whole 2 meter band being am- 
plified at once by 30 dB or more, and large 
voltages may easily result when strong signals 



22 



73 MAGAZINE 



INPUT 



o.e-to 

JOKANSON £954 



•fl2'J& O 




/as OUTPUT 
■^TO RCVH 



con, PATA 

Ll-€TURW$ Naie 1/4' LD.,3/4* L6-, 
TAPPED I TURN rftOM G»0 END 

LE,L3-0^2i^ OEUAVAH RFC 

L4' 5H/2 TURNS NO. IS 1/4* I. D., 5/4* L©, 

L5,L7- 5 TURNS WO. 24 ON MtCROMETALS T-30-|5 
TOROIO CORE (A COfL SfMILA^ TO L4 
COULD BE SUSSTITUTEDJ 

LS- 13 TURNS NO, 26 CLOSEWOUNO 
ON 1/4" SLUG-TUNEO FORM 

LQ- 3.3 jjH OELAVAN RF€ 



j^LOW BAND 
t»ANT 



Fig. 1. Schematic of K6HM0's low-noise, fow*cross 
modulation two meter converter using inexpensive 
field effect transistors (FET's). This converter can 



give a noise ffgure of under 2.5 dB, gain of 27 dB 
ond very good rejection of cross modulation prod- 
ucts. 



are present Some readers may have had 
trouble with FM and TV stations showing tip 
in their transistor converters or receivers- It is 
usually insuflBeient front end selectivity and 
resultant cross modulation which are respon- 



The FET at VHF 

The field effect transistor has an almost 
perfect squaie-Iaw transfer function, i.e, odd 
order terms are almost nonexistent- The result 
is greatly improved cross modulation perform- 
ance. In addition^ recently introduced FETs 
are capable of very low noise performance in 
the VHF and UHF range. Noise figures as 
good as any vacuum tube or bipolar transistor 
are readily obtainable* 

The device selected for this converter, the 
T1S343 is made by Texas Instiuments and is 
encased in an economy plastic package. The 
price is $2.80. The TIS34 is very similar to 
the 2N3823— it appears to be the same chip— 
w^ch has been available for some time for 
aliout $12. The data sheet for tlie 2N3823 is 
much more complete than the one for the 
TIS34 and it was used in the design of this 
converter. 

Construction 

%The FET converter shown in Fig. 1 was con- 
ructed on a piece of printed circuit material 
cut 4x6 inches. The completed converter was 
moimted in an upside down 4x6x1/2 inch 
aluminum. 



The circuitry is very convenrional and 
makes use of single-tuned transfomiers for 
impedance matching and to provide the re* 
quired selectivity. 

The noise figure test for the TIS34 specifies 
a source impedance of 1000 olims. This is ob- 
tained with the tapped input inductor. The 
drain load impedance is simply the parallel 
combination of the real part of the FET input 
impedance and Rl* The imaginary part of the 
input impedance is tuned out with L4 and C2. 
L£ is a standard rf choke used for neutraliza- 
tion by resonating with the drain-gate capaci- 
tance at 144 MHz, The second stage is essen- 
tially identical to the first. The rf amplifiers 
are simple, stable, and use very few compo- 
nents. 

The design of the mixer was almost en- 
tirely emj)irical because of the lack of large 
signal data. The best compromise between 
noise figure and gain resulted when the FET 
was biased to a few hundred microamperes 
with the source resistor, (remember cathode 
bias) and then driven on with the local oscil- 
lator power. Better performance was obtained 
with the available local oscillator power when 
the local oscillator was introduced at the gate 
ratlier than at the source. The mixer output 
circuit is resonant at 28 MHz. The 51-ohm 
resistor terminates the receiver used with tlie 
converter and with L6, C6, and C7 determines 
the drain load impedance of Q3. 

The local oscillator circuit is the same as the 



OCTOBER 1966 



23 




HP 




















• 


^ 




h 








-*^' ^ -T. .. 



Top view of the FET two meter converter. 



Bottom view of the FET two meter converter* 



one used by Frank Jones, W6AJF, in his con- 
verters shown in tlie June issue of 73. Briefly, 
L8 and C5 are resonant between the funda- 
mental and the tliird overtone frequency. In 
this case L7 and C4 resonate at twice the third 
u\ertone frequency at 117 MHz, This results 
in an if frequency of 27 to 31 MHz, Other if 
frequencies could be used merely by selecting 
another crystal freciuency and scaling tlie 
mixer output circuit to the desired frequency. 
For example, for 14 to 18 MHz use a 63 MHz 
cr\'stal and double L6, C6, and C7. 

The switch at the if output is used to switch 




VARIABLE 
ATTENUATOR 



DRAKE SB 
RECEIVER 



@€N. NO. 2 
|4« mm 
HP 60e€ 



VTVM 
HP 400 Q 



Fig. 2. Test setup used for cross modulation meas- 
urements. 



the communications receiver between the con- 
verter and a low frequency antenna. 

Performance 

The completed converter has a noise figure 
of just under 2»5 dB measured on a Hewlett 
Packard Noise Figure Meter, Tlie gain from 
144 to 28 MHz was measured and found to 
be 27 dB, Cross modulation measurements 
were made in order to compare perfonnance 
with a conventional bipolar transistor con- 
verter. The setup shown in Fig, 2 was used 
for these measurements. The attenuator was 
included in order to assure that cross modula- 
tion observed was not produced in the com- 
munications receiver, 

The converter-receiver combination was 
tuned to generator #1 at 145 MHz. Generator 
#1 was modulated 301? with a 1000-IIz tone, 
and the output level to the converter was 5 
microvolts. The modulation on generator #1 
was then turned off. Generator #2 was tuned 
to 146 iMIIz and modulated 30$ with a 1000- 
Hz tone. The outptit level of generator #2 was 
then increased until tlie signal from generator 
#1 appeared to be modulated 1% (30 dB down 
on the VTVM). In ordinary use 1% represents 
a just detectable case of cross modulation. 

This test was performed on both the con* 



24 



73 MAGAZINE 



► 



verter described litre and another using bipolar 
transistors. The results are shown below along 
with other comparative measurements: 

Bipolar FET 

Noise Figure 3.1 dB 2.4 dB 

Gain 24 dB 27 dB 

Bf input for 
i% cross mod. 0.5 mV 27 mV 

As can be seen the FET lives up to the 
claims made for it. 27 mV at the input means 
about 1 volt at the gate of the mixer where the 
cross modulation should be occurring- This im- 
proved performance means that fellow down 
the street would have to increase his power 
2916 times in order to produce the same 
amount of interference. 

On the air tests at the author's shack have 
confimied the improvement in cross modula- 
tion resistance. With the bipolar converter, 
the modulation of a local repeater could be 
heard on every other signal on the band. With 
the FET converter, no detectable cross mod* 
ulation has been observed from the repeater 
or any other local station in several months of 

operation- 
Miscellaneous 

Power for the con\ erter here is supplied by 
a transistor transmitter used with it* There is 
plenty of room, however^ to build a power 
supply into the converter. A suitable power 
supply is shown in Fig* 3, 

The trimmer capacitors used here are quite 
expensive. They sell for more than tlie FETs, 
Almost any other good quality t}^e would be 
a suitable substitute* Small ceramic trimmers 
could be used at a considerable saving. 
k, For those who have an especially acute 
icross modulation problem, and who are willing 
to experiment, even better cross modulation 
performance than that obtained with this con- 
verter could be obtained with the common 
gate configuration* The common gate config- 
uration is similar to grounded grid in a vac- 
uum tube. The noise figure will be about 0.5 
dB higher and the gain a little lower, but be- 
cause of the lower impedance lev^els the volt- 
ages will be lower and remember it is tlie 
voltage that leads to cross modulation, 

. . , K6HM0 




OTO CONV. 



E5V 



Fig. 3. Power suppfy suitable for use with the FET 
converter- 



CAVEAT 
EMPTOR? 



AIO say the buyers of 73's fast growing 
want ad section- Caveat Emptor? CE*s low 
price of $2 for 25 words (non-commercial 
ads) brings excellent results. You know why. 
73 is read by the active, money-spending 
hams. Our want ads are the cheapestp and 
they're also set in clear, easy-to-read type 
with lots of space between them. And we're 
not nasty about the length, eithen round the 
price off to the nearest dollar ($1 minimum) 
if you have more or fewer than 25 words. 

We don't encourage businesses to advertise 
in Caveat Emptor? since 73's regular space 
rates are so low^ — as little as $18 for a l/16th 
page display ad« But if you insist, the charge 
is $5 for 25 wordSp or $50 in advance for 25 
words per month for a year. 

A few hinte lor your ads. Type your copy. 
Don't abbreviate since you pay for words^ not 
space. Include your full name and address as 
well as your call; not all hams have a Call- 
book, though they certainly should. We put 
the first few words in bold face capitals, so 
make them attract attention. Don't put "For 
Sale" in the ad; everyone knows that's what 
the ad is for unless you say otherwise. 

Please type your ad on a large, plain piece 
of paper. 



Send money and ad to: 



Caveat Emptor? 

73 Magazine, Peterborough, N.H, 03458 



OCTOBER 1966 



IS 




Wode Williams K5ILG 
2327 Wheeling Avenue 
Ei Paso^ Texas 



Electronic Thermometer 



Although this instrument is not exactly in 
the category of ham radio equipment, it is of 
an electronic design and an exceOent project 
for the gadget builder. It's an electronic ther- 
mometer that may be used for a remote tem- 
perature reading witli a scale from —50 de- 
grees C to 250 degrees C, You can also cali- 
brate it in Fahrenheit degrees. 

Tlierniistors are thei-mally sensitive resistors 
whose primary function is to show a change 
in electrical resistance with a change in tem- 
perature. They are extremely sensitive to 
minute changes in temperature* A characteris- 
tic of thermistors is their wide range of nega- 
tive or positive temperature coefficients. Be- 
cause the resistance of a thermistor is a func- 
tion of ambient temperature, thermistors can 
be effectively used in devices to measure or 
control temperature. The high resistance of a 
theiTnistor as compaied to the resistance of 
long leads makes possible accurate tempera- 
ture measurements from remote locations • . . 
such as your operating desk. 

The bridge circuit shown in Fig. 1 may be 
used as a deflection device where the output 
can be calibrated directly in temperature* An 
0-1 mA meter is used as the indicator. It is a 
GE Type D,0.91, Catalog No, 512x22. The 
thermistor is G,E, 3D-054- lOOO plus or minus 
1% at 25 degrees C. For cahbration of the 
bridge circuit close the Null Sv^tch (Rl) and 
adjust the potentiometer for minimum read- 



NULL 



500 





CLOSE » ADJUST 
FOR RJU. SCALE 



V^/O-lfnA 



Fig. T. Bridge type electronic thermometer, T fs a 
Gt thermistor os discussed in the text. 



Fig. 2, Ohmeter type electronic thermometer, T is 
a thermistor. It's discussed in the text. 

ing. Open the Null Switch and adjust R2 
(150Q pot) for calibratioD. Switch can be 
miniature (or standard) push button type for 
temperature readings. This bridge circuit can 
also be used as a nuU type of bridge where 
the variable resistance is adjusted to null the 
bridge output and cahbrated in terms of tem- 
perature. The five resistors in this ciicuit must 
be of the precision type for accuracy. 

The ohnimeter type circuit as shown in Fig, 
2 employs the GE TheiTnistor No- 2D-1119, 
2.32 kQ, plus or minus 1% at 25 degrees C* 
An 0-1 mA meter is used as the indicator. It 
is G,E, Type D,0. 91, Catalog No. 512x22. 
Tlie 336Q resistor must be one of precision 
l>pe. For accuracy, components of best qual- 
ity are recoromended* The switch is a minia- 
ture or standard pushbutton type for tem- 
perature readings. If your dealer cannot supply 
you with the thermistor contact the General 
Electric Company^ Magnetic Materials Sec- 
tion^ P. O, Box 72, Edmore, Michigan. The 
price is $5.10 each, 

Cahbration of the meter is not difficult, al- 
though it takes a little time to calibrate the 
entire scale for normal use such as from —32 
to 120 degrees F. A comparison thermometer 
of good quality is recommended. 

It might be possible to use the tliermistors 
which are incorporated in radiosondes and 
available at some surplus outlet. Inasmuch as 
these circuits are critical, considerable experi- 
mentation may be necessary to develop an 
accurate themiometer. 



73 MAGAZINE 



r 



r 




1000 watt (p.e.pj mobile antenna 
at a mini-pjower price! Quick-con- 
nect high power inductors for 160*- 
80-40-20-15*10 meters have excep- 
tional figure of merit — "Q" — that 
measures approximately 230 on 80^ rises to 350 
on 15 meters. Webster invites comparison of this 
shy power antenna particularly its high efficiency 
space-wound coils, suspended — not molded ^ — in- 
side a protective all-white tenite housing. Com- 
pare also the precision machined hinged column 
assembly that releases coil/whip for right-angle 
taydown— forward or to the rear. Lockup into 
operating position is equally fast, tn stall BIG-K — 
give your mobile signal a real sendoff. Two column 
sizes for bumper and deck mounting with overall 
lengths, respective fy, of 93" and 1T\ And use the 
money yoo save to buy a fine Webster mount. 



Band-spanner 



Want a fully streamlined car an- 
tenna that will handle 500W p,e.p.? 
Buy Band*spanner as thousands 
have over the past sixteen years. 
One clean-cut antenna — nowhere 
over 11/3" in diameter — that delivers big sky power 
on 80-40-20-15-10 meters plus MARS, Band-change 
in seconds too just by raising or lowering the top 
whip (which contacts a section of any of the inter- 
naliy exposed inductor turns) and exact resonance 
on any in -band frequency. Band- spanner— truly 
streamlined — de-emphasizes the appearance of a 
fair size antenna on a new car. It has a two-tone 
fiberglass column and an attractive, epoxy*sealed 
loading section that bfends both with car and 
surroundings. Two column lengths? Model ABB, 
117* overall extended* 63" tetescoped and Model 
ABDp 93" overall extended, and 60^ telescoped* 



160-meter coil 300W p.e.p. 



Model TH5AP, 

de luxe 3-hole 
mobile mount. 





Model BCM, 
bumper chain mount, 
(spring not supplied) 




y^tmm-:. 



Model SHM, 
single hole de luxe 
mobile mount. 




Write today tor free BtG-K and Band-spanner brochurdf 



RAYTHEON COMPANY 
213 East Grand Ave» South San Francfsco, Calif. 94080 




OCTOBER 1966 



27 





^ 



Herbert Brier W9EGQ 
385 Johnson Street 
Gary, tndiQna 46402 



Controlled Avalanche 
Silicon Rectifiers 

Another improvement in solid-state electronics 



To explain what Controlled Avalanche Sili- 
con Rectifiers are and whv thev are better 
than conventional silicon rectifiers^ we must 
first review a few rectifier facts* 

Over the past several yearSj siUcon rectifiers 
have been gratluany replacing vacunni-tube 
rectifiers in the power supplies for electronic 
equipment, because of their high efiiciency, 
compactness, and convenience, Hmvever, as 
almost everyone wlio Las used them has dis- 
covered, silicon rectifiers are not foolproof^ 
primarily because of their severe voltage limi- 
tations. 

Under controlled conditions, silicon rectifiers 
with voltage ratings well above 1000 volts 
can be made, but 400 to 600 volt units are 
much easier and less-expensive to make. 

When a rectifier is forward biased— anode 
positive with respect to its cathode— it will 
pass its rated current with a very small voltage 
drop across it. But when the rectifier is reverse 
biased (hooked up backwards, as it were), 
little current will flow through it in the re- 
verse direction until tlie voltage reaches a 
critical value. Above this critical peak inverse 
voltage (piv) or peak reverse voltage point, 
the reverse current increases very rapidly. 
"Avalanches," as the solid-state engineers say. 
The combination of high voltage and high 
current can destroy a rectifier in microseconds. 

Actually, the normal voltages present in 
solid-state rectifier systems ai'e only a minor 
problem, because they are easy to determine. 
The big trouble is with voltage transients in- 
side or outside the power supply. For example, 
lightning strikes have produced instantaneous 
Voltage peaks up to 5600 volts on regidar 120 
volt power lines. In addition, an arcing switch, 
a chattering relay, a blown fuse, a momentary 
power interruption, or the opening or closing a 
switcli at a crucial point of the AC cycle can 



all generate transient voltage spikes ten times 
as great as the normal peak inverse voltages 
across the rectifiers and blow them instantly. 

Surge arrestors connected to various parts 
of the power supply circuit can cut transient 
voltage spikes down to size. Bnt the rub is 
that they may cost far more than the rectifiers 
they are supposed to protect. Furthermore, 
the only way to detennine the proper values 
for many protective devices is to measure tlie 
transient voltages on a fast writing oscilloscope 
or a peak -reading vtjlt meter and experimen- 
tally adjust values to reduce the transients to 
the lowest practical value. 

Unfortunately, transients have a nasty habit 
of appearing to be cured and then popping up 
worse than ever when least expected. As a 
result, several rectifiers ma>' be destroyed be- 
fore the transients are suppressed* 

Now, at long last, we come to the Con- 
trolled -Avalanche Silicon Rectifier, Remember 
that the reverse current through a conventional 
silicon rectifier "avalanches" or increases very 
rapidly when the peak inverse voltage across 
the rectifier exceeds a critical breakover value 
and destroys the rectifier. Taking a critical 
look at the well-known fact that, while tran- 
sient voltages in rectifier circuits frequently 
reach very high peak values, they are nomially 
of very short duration and contain little 
energy, the rectifier engineers reasoned: if we 
can cmtse the rectifii'f's hack resiMance to de^ 
crease eoen more rapidly thmi in a contjefi- 
tional dhcon rectifier at the breakover point, 
the Jaw remstance will present a virtual short 
circuit to the transient and will chop off the 
voltage spike before it can damage the rec- 
tifier. 

To achieve their aims, the rectifier engi- 
neers carefully refined the siUcon from 
wliich the new rectifiers were to be manu- 



28 



73 MAGAZINE 



p 



factured so that its resistivity would be uni- 
form throughout tlie entire slab, instead of 
being composed of layers of different resis- 
tivities as in less-carefuUy processed silicon. 
In addition, they doped the silicon very pre- 
cisely while forming the rectifying functons to 
make their interfaces as smooth and as free 
of voids as possible. 

In operation, the controlled avalanche rec- 
tifier performs exactly as theory predicted it 
would. Under normal conditions^ it performs 
just like a conventional silicon rectifier, but 
when a transient voltage peak comes along, 
the avalanche effect slices off the peak before 
it can injure the rectifier , 

High Voltage Operation. Controlled Ava- 
lanche rectifiers have another advantage in 
high-voltage power supplies. As mentioned 
earlier, silicon and other solid-state rectifiers 
are strictly limited as to the amount of voltage 
they can withstand. Consequently, to rectify 
high voltages with them, it is necessar>^ to 
connect a number of low-voltage units in se- 
ries. But this procedure produces complica- 
tions with ordinarv silicon rectifiers. 

Conventional rectifiers show considerable 
difference between units in their back resist- 
ance and in the length of time that it takes 
them to recover their back resistance when the 
applied AC voltage swings from positive to 
negative. For thee reasons ^ it is usually neces- 
sary to connect equalizing resistors and capaci- 
tors across each rectifier in tlie string when 
conventional silicon recitifiers are connected 
in series, 0.02 ixf capacitors and 1000 olims per 
volt of rectifier piv are typical values. 

But the controlled characteristics of con- 



trolled avalanche rectifiers usually eliminates 
tlie need for equalizing resistors and capacitors 
in series circuits. 

Selecting Controlled Avalanche Rectifiers. 
Several of the well-known rectifier manufac- 
turers, such as G£, RCA, and Sarke^ Tarziiin, 
are manufacturing controlled avalanche recti- 
fiers. Sarkes Tarziam, in fact, is now furnish- 
ing the controlled avalanche type of rectifiers 
under the same t>T>e numbers and prices as 
of their older rectifiers which did not have 
this feature. Some other manufacturers make 
both controlled avalanche and conventional 
silicon rectifiers, and still others make only the 
conventional t>T>e. You, therefore, must exer- 
cise a little care in your selection if you w^ant 
the new^ controlled avalanche tvpe- 

One way to identify controlled avalanche 
rectifiers is to check piv's in your electronics 
parts catalogue. Two of them are listed for 
the controlled avalanche rectifiers. Use tlie 
lower figure for designing the power supply. 
The higher * non-repetitious*' or transient piv 
is the point at which transient voltage spikes 
will be chopped off. 

Incidentally, when conventional silicon rec- 
tifiers are replaced with controlled avalanche 
rectifiers, it is not necessary to remove any 
protective devices already installed in the 
power supply. Leave them in for an extra 
safety factor, because controlled avalanche 
rectifiers are not cure-alls for all rectifier ills. 
Extra-energy transients can still damage a 
controlled avalanche rectifier, if the rectifier 
is not consei^vatively chosen. But the impor- 
tant fact is tliat the odds go up in your favor 
when vou use them. - - - W9EGQ 



The Touch Keyer 



This simple circuit allows key-type opera- 
tion without a key. The operator just touches 
the grid and taps out the CW with his finger. 
When you touch the sensor plate, a small cur- 



Fig. 2. The touch grid cwiho 
con be mode from etched 
circuit board like this, or 
con simply be two wires. 



"Q OUTPUT TQ 



^ KEYIWS cif«urT 




■5 VAC 

eOLATKW 
XFMR 

(TAIAD K»K) 






i & \ 




GE cioe & 



TOtXti PR 10 
(SEE TEXTJ 




^rFZ9O0O ACS 



Fig. 1, Here's the ideal substitute for a key: 
Touching the touch plate with your finger turns 
on the silicon controlled rectifier (SCR)^ which 
throws the relay to key your tronsmitten 



rent is applied to the gate of the SCR from 
the battery BL This turns on the SCR, which 
supplies half -wave power to relay RYl to en- 
ergize the relay. Diode CRl provides a return 
path for the relay-induced voltage and is nec- 
essary to prevent 60 cycle relay chatter. The 
SCR triggers when a low level positive current 
is applied to the gate of the SCR and turns 
off as soon as the current is removed. The 
low battery voltage along with the use of an 
isolation transformer provides no hazard to the 
operator, - - . David Metzger K8GVK 



OCTOBER 1966 



29 





Jock Alt-house WA6CEZ 
Rt 3 Box 744-B-2 
Escondido, Calif. 92025 



The straight key Is the basic CW instrument. This 
is E. F. Johnson's model 1 14-310. 



Look What's Happened to 

the Telegraph Key! 



CW is not yet dead* As a matter of fact, if 
tlie current ollerings of the telegraph key 
manufacturers are any mdicatioiij it may be- 
come as popular as siiigle-sideband. 

The traditional meclianieal keys are still 
around and in a variety never available before. 
But the big new sound on tlie CW bands 
comes from the keyers-^electronic devices 
using space-age circuits to make sending easy 
and more precise* 

The electronic keyers require SPDT key 
action. So, for the first time in many years, tlie 
**Sideswiper" key is in the spotHght. 

And tliere are ke)ers with features that re- 
sult, strangely enough, from the popularity of 
voice-only SSB tiansceivers. 

The new look in CW has brought forth a 
bewildering array of keys and keyers to suit 
the purposes of any CW operator. In tbis arti- 
cle we will describe the relative merits of the 




A semi-outomatlc key by E, F. Johnson. Model 
114.520, 



3D 



different keying methods and list the features 
of commercial keys and keyers. 

Straight keys 

The time-honored straiglit key is univer- 
sally present in ham shacks and commercial 
radio rooms. With its round black knob it 
hasn*t changed much since before radio was 
born. Unless the FCC changes its mind about 
code exams ifs likely to be around for a long 
time to come* 

It's the only key recommended to the be- 
ginner for code practice and for operating on 
the novice bands. The amateur whose primary 
interest is in phone operation may nev^er want 
anything more elaborate. 

The E, F, Johnson Co, makes a complete 
line of sbaight keys ranging in price from 
$2,40 to $7.95. The lower priced keys are de- 
signed primarily for code practice. They have 
phenolic bases than can be cracked if screwed 
too tightly to the operating table. The more 
expensive models feature metal bases^ smoother 
bearings and more precise adjustments. Keys 
aie available wiUi shorting switches (a feature 
impc*rtant in wire telegraphy but not usually 
needed by the amateur radio operator) and in 
different decorative finishes. 

The Brown Bros, model ST has a hea\^ 
S(iuarc l)ase that will not tilt under normal key- 
ing pressm'e. It is useful on a glass-topped 
desk where it would be diificult to screw down 
a conventional key, 

73 MAGAZINE 




Left, Brown Bros, rnodel UTL sideswiper has tap* 
ped holes on front and bottom for mounting In 
custom electronic keyers. Right. For those who 



need o complete sideswiper, the UTL con be pur- 
chased mounted on a square bose. 



I 



Semi-automatic keys 

It's entirely possible to send CW at 30 wpm 
and above witli a stiaight key. But it is difB- 
cult and soon becomes tiresome. ThuSj for 
many years, operators have favored the ^'bug** 
or semi-aiitomatic key. It makes a string of 
dots when the lever is pressed to the left. 
Dashes are made manually by moving the 
lever to the right* It ^ a vast improvement 
over the straight key for sending speeds above 
15 wpm. 

Although the semi-automatic key is sub- 
stantially more expensive than the straight 
key, it stands out as a star performer in the 
fight against inflation. In 1925 the Vibroplex 
Co, advertised their "Bug" at $17* Forty years 
later their "Champion*' model sells at $17*95. 
Odier models wdth jeweled bearings, attractive 
finishes, and complete witli cord and wedge 
range up to $33.95, 

The wedge sHps under the circuit closing 
switch of a straight key (if it has one) so that 
the semi-automatic key can be attadied to the 
tiansmitter keying circuit without permanent 
%viring- It*s useful to the commercial operator 
who takes his own key to work with him but 
is not generally used by amateurs. 

The standard semi-automatic key is for 
right-handed operators but left-handed models 
are available* 

Electronic Iceyers 

The electronic keyer is the device that sits 
in the spotliglit today. It*s truly a product of 
the age of electronics. 

The multivibrators, gates, binary counters 
and otlier circuits that came into widespread 
use with the advent of Radar led to experi- 
ments with electronic keyers more than twenty 
years ago. In the past few years several com- 
mercial designs have appeared. 

The electronic keyer uses a two-way lever. 



Press to the left and it makes a string of dots; 
press to the right and it makes a string of 
dashes. But that's not all. Just as a doughnut 
is not complete wltliout a hole in the center, 
Jilorse code is not complete without proper 
spacing between the dots and dashes. Elec- 
tronic keyers form the spaces with their "self- 
coniplcling" aetion. 

Here*s how it works: Press the key to make 
a dash. Once the key has been lightly tapped 
the events to follow are temporarily out of the 
operator's control The keyer will make a dash 
and then it will make a space. After the dash 
and the space are over the operator regains 
control and can call for the next dot or dash, 

It*s because of this ^^self-completing*' feature 
that the Brst try at operating an electronic 
keyer can be a frightening experience. If the 
key is not pressed at the proper times the 
output is gibberish. But, once the technique 
is mastered, code spouts out of an electrom'c 
kej^er with a machine-hke precision that is 
pleasing to the ear. Dots, dashes and spaces are 
perfectly "weighted," that is, dots and spaces 
are exactly % as long as dashes, 

Hallicrafters' model HA-1 at $79,95 is a 
t>q>ical keyer. It will operate at speeds from 
10 to 65 v^rpm, has the self-completing feature 



r^*"^ — -^^"^ 



^ 



^': 




,v....-- . . I . • ■ ■ y^ ^^ y.: 



The Vibroplex ''Blue Racer" h typical of the semi- 
automatic keys. The wedge, in foreground, con- 
nects to the station's straight key. 



OCTOBER 1966 



31 






$ 





Etectrophysics Corporation's '^Autronic" key typi- 
fies the new generotion of sideswipers* 

and includes an audio oscillator to monitor 
sending throiigli headpliones or on its self- 
contained speaker. 

Electrophysics Corp* markets a transis- 
torized keyer at §79.50 with similar specifica- 
tions. The panel lettering has been rotated 
45° so it IS readable with the keyer horizontal 
or set on end* 

Sideswipcrs 

The keyers described above require a sepa- 
rate key for their operation. It must have a 
SPDT action J one contact for dots, another for 
dashes. Pioneer builders of electronic keys had 
to make their own. One metliod was to adjust 
a semi-autoniatic key to have continuous clos- 
nre on tlie dot side* Another was to place two 
straiglit keys back- to-back. 

Today, ke>^ designed especially for elec- 
tronic keyers are available- Electrophysics Cor- 
poration's "Autronic" key, $19,95, takes less 





mi^imim^^ 



The "Autronic" key by Electrophysics Corp, Only 
2" high it can be ploced on end to save desk 
space. In its semi-Qutomatic mode dashes are 
made manually. This mode is used "key down" 
for transmitter tuning. 

space on the operating table than either a 
straight or semi-automatic key. 

Brown Bros, model UTL, $10,95, is a key 
mechanism without a base for mounting on a 
home-brew keyer. Their interesting model 
CTL, $18.95, has a straight key and a side- 
s wiper on a single base. 

Both Vibroplex and Productive Tool make 
keys for electronic keyers that are sinular in 
appearance and construction to semi-automatic 
keys. 

SSB keyers 

Tlie keys and keyers described above are 
designed to key the transmitter carrier. 

But what about the transmitters that don't 
liave a carrier to key— SSB suppressed carrier 
transmitters? A few of the popular tiansceivers 
have provision for carrier injection so that they 
can be used for CW. Many do not 

Sideband Engineers lias the answer to C\V 
for tlie SSB operator in their **Codapton" It 
works tliis way: Connect an audio oscillator to 
the microphone jack of a SSB transmitter and 
out comes a CW signal Its frequency is above 
(USB) or below (LSB) the suppressed carrier 





Left, The squore base and rubber feet of this 
Brown Bros, key let it sit on the desk without 
screws. The double layer knob is known as the 




"Navy knob/' Right, An unusual key by Brown 
Bros, On one bose is a key for an electronic keyer 
and a stondard straight key. 



31 



73 MAGAZINE 




«! 



THE DAVCO 




COMMUNICATIONS OECENER 




«l 



> CompleU ham-Eiind ooveragi SO-10 meters 
anil portfon ol 6 meters * Stafidard>^eqiJipnierTt 
9,5-10.5 M(^ band provides WWV and 31 meter 
SWLband«ThreepBSiftttnse!ectivitYforiiptimum 
lideitty and QRM rejectian * Crystat-EontrQlted 
BfO: scpirati AM arid Product deieclors; AF 
and HF gain contrels ' Full AGC with selectable 
decay ttme: S-Meter; illuminated dial * Fly- 
wheel tuning drive with high^ratia split gears; 
dtrect eadbration an aH bands * Tunable reiec- 
tton notch filter: extremely eHective nuist 
timlter • Transmitter type VFO: crystal con- 
trolled first oscillator; buMt in crystal caltbrator 
* Low power eonsumption., permitting 12V 
battery operatEon when desired; AC supply 
avaffafifi * Full transistnriiation, diode stiec- 
livky switching, plug-in module construction, 
highest quality components * Rugged, stable 
extruded aluminum chassis .for toitrema sta- 
biltty; textured gray metal cabinet: FULLY 

GUARANTEED, 



n 



■I 



Compact, high performance, all solid-state 
receiver for amateur applications featuring 

FIELD-EFFECT TRANSISTORS 

Developed especially for the sophisticated amateur who knows enough to 
demand the fines!. The DAVCO DR4D is amateur designed and professionally 
engineered to provide exceptional performance under exirefne enviroa* 
mental conditions and combines advanced design with simplicity of opera- 
tion. It provides all the latest state of-theart techniques in an ultra-compact 
unit (just 4"h x 7-1/8' w x 6"d). Every DAVCO OR'30 is hand^crafted, 
inspected on the line during production no less than 60 times and put 
through rigorous final testing before serial number and warranty are 
awarded. The DR^SO utilizes Field^Effect Transistors in RF stages to assure 
greater sensitivity, superior image rejection and unbelievable freedom from 
cross-modulation or strong-signal overloading. You'll dig out the weak 
ones with ease, even when the ham down the block is on with bis KW. 
Today's crowded bands demand DAVCO DR>3D performance. Ask tha ham 
who is using one now, check the many plus features included at no extra 
cost and you'll discover why Davco is the leader in providing amateyrs with 
the most advanced in solid-state electronics. 

DAVCO DR-30 RECEIVER $389S0 



For further information and illustrated brochure, write: 
DAVCO ELECTRONICS, Inc. P.O. box 2677, 2024 S. Monroe St. • Tallahassee, Ffa. 32304 



OCTOBER 1966 



33 




J 



The Heathkit HD-IO has a poddle similar to those 
of semi-Qutomotrc keys. The ''hold" position of 
the on-off switch is for transmitter tune-up. 

frequency by the audio oscillator frequency. 
Key the audio oscillator and, presto, you're 
on CW. 

The "Codaptor" also contains delay circuits 
that close the T-R relay of a transceiver before 
the keyed tone reaches the transmitter and 
keeps the relay closed, VOX fashion, for a 
time delay adjustable by a front pane! controL 

Integral electronic keyers 

Two recently introduced keyers come with 
a built-in key mechanism. Waters Mfg. Co. 
offers a fully equipped package at $92.50. In 
one box it has a transistorized electronic kever, 
a key, a tone oscillator for keying SSB trans- 
mitters and for monitoring, a mixer to combine 





The built-in key of the Waters keyer requires only 
20 grams pressure for operation. This l<:eyer will 
operate for more thon 400 hours on its self-con- 
tained batteries. 

the station receiver output with the sidelona 
oscillator, and its own batter)^ supply. This, 
at present, seems to be the Cadillac of keyers. 

For the do-it-yourself constructor there is 
the Heatli model HD-10. The kit, at $39.95, 
has an integral key and operates from 115 V 
ac. It will also run on an external 45 volt 
battery. 

Most straight or semi-automatic keys will 
switch a good deal of power. Electronic keyers 
have specified maxim utn voltages, currents, 
and power that they will switch. They should 
always be operated within the manufacturers 
ratings. 

The switching ratings and other data on 
representative keys and keyers are included in 
the following table. Any of the manufacturers 
listed will be happy tn provide fuither infor- 
mation. 

. . . ^VA6CEZ 




Ha Hie rafters model HA-l keyer is based on a de- 
sign by W9T0. The function switch provides two 

speed ronges and a ''hold" position that keeps the 
transmitter on for tuning. 



SBE's "Codoptor" allows an SSB transceiver to be 
keyed with a straight or semi-automatic key. After 
the key is opened, the transceiver T-R relay re- 
mains closed for a time selected by the front-panel 
"Delay" control. 



34 



73 MAGAZINE 



fvianuracrurer 


Model 


Price 


Type 


Ameco Equipment Corp. 
1 78 HerrJcks Rd. 
Mineola, LJ., N.Y. 


K-1 
K.2 
K-3 
K-4 


$ 1.00 
$ 1.45 
:; 2.35 
!i 3.00 


Straight Key 
Stroight Key 
Straight Key 
Straight Key 


Brown Bros. Mach, Co. 
5370 Southwest Ave. 
St. Louis 39, Mo. 


ST 
UTL 


$ 6.95 
$10.95 


Stroight Key 
Sideswiper 




BTL 
CTL 


$14.95 
$18.95 


Sideswiper 

Sideswiper 
Straight Key 


Electrophysics Corp. 
898 West 18th St. 
Costa Mesa, Calif. 
92627 

"Autronic" 




$19.95 
$79.50 


Sideswiper 

E ectronic 
Keyer 


Hollicrafters 

Fifth & Kostner Avenues 

Chicago 24, III. 


HA-1 


$79.95 


Electronic 
Keyer 



Heath Company 
Benton Horbor, Mich* 
49023 

''Heathkir' 



HD-10 



$39.95 



Electronic 
Keyer Kit 



Features 

Phenolic base. 
Adjustable beortngs. 
Metal base. 
Brass base. Shorting switch. 

Heavy base. For glass-top 

Key only. For home-brew 

keyers. 

Same as UTL with heavy base 

Two keys on one base. 



Compact. Use on gloss-top 

desks. 

Transistorized, compact, for 

grid-block keying, switches 

105 V @ 80 mA. High power 

switching transistors avail- 

oble. 

Mercury- wetted relay switches 
5-amp 250 V 250-wQtts max. 



Transistorized, integral key, 
for grid block keying, switches 
negative 105 V @ 35 f^iA- 



E. F» Johnson Co* 
Waseca, Minn. 



Productive Tool & Mfg; 
Co., Inc. 
9 Market Street 
Stamford, Conn. 

Sideband Engineers' 
317 Roebling Rood 
South San Francisco, 
Cotif, 



114-300 
114-301 

114^310 
114-310-2 
1 14-31 1 
114-31 1-3 

114^100 
114-100-3 
114-520 
114-500 

115-501 



*# 



Nikey" 



if 



$ 2.40 
$ 2.50 

$ 3,50 

$ 4.25 

$ 5,50 

$ 6.50 

$ 6.95 
$ 7.75 
$17.75 
$20.30 

$25.50 



Straight Key 
Straight Key 

Straight Key 
Straight Key 
Straight Key 
Straight Key 

Stroight Key 
Straight Key 
Semi-automatic 
Semi-outomatic 

Semi-automatic 



$17.95 Sideswiper 



Codaptor" $39.95 SSB Keyer 



Phenolic base. 

Phenolic base. Adjustable 

bearings. 

Metal base. Takes wedge. 

Shorting switch. 

1 1 4-3 1 but chrome plated. 

1 14-310-3 but chrome 

plated. 

Brass base. Fully adjustable. 

1 14-100 with shorting switch. 

Circuit closing switch. 

Fully adjustable, Ks" contacts. 

Fully adjustable, Vi" contacts. 

Dual lever, heavy base. 



T-R relay control, adjustable 
VOX delay. 



I 



Waters Mfg. Inc, 
Wayland, Moss. 
"Codox" 



The Vibroplex Co., 

833 Broadway 
New York 3, N.Y, 



Inc, 



361 



$92.50 



Electronic 
Keyer 



Transistorized. Integral key. 
Switches 250 V dc, l-omp, 
15-watts max. Reed relay 
switch. Battery operated (bat- 
teries not supplied). 



Vibro- Keyer 


$17.95 


Sideswiper 


Heavy base. Fully od jus table. 


Champion 


S17.95 


Semi-automatic 


Heavy base. 


Blue Rocer 


$22.45^ 


Semi-automotic 


Compact size. Jewelled 
movement. 


Presentation 


$33.95 


Semi-automatic 


Gold plated, Fulfy ad|ustable. 



I 



* — Cord and wedge at extra cost, 

■'The Bug" and "Vibroplex" are trade marks of the 
V^ibroplex Co. 



'Codax" is a trade mark of the Waters Mfg, Co* 
^'Heathkit" is a trademark of the Heath Co, 



OCTOBIR 196$ 



35 




. ^^.^...^ .^-. MAXIMUM PERFORMANCE 

LOOKING FOR proven reliability 

»v«r«m>«ww « v*« SUPERIOR CRAFTSMANSHIP 




MARK I LINEAR AMPLIFIER 

Five band, 2000 watts PEP input. 
Uses two Eimac 3-400Z or two 
Amperex 8163 triodes, htas built-in 
power supply. 

PRICE $475 



TUBES $68 




MATCHING AC SUPPLY 

with speaker, phone jack. 

MODEL 117-XC.... $95 

MODEL 230-XC 

for 230 volts $105 

DC MODULE Converts AC supply 

to 12 volts DC for portable or 
emergency operation. 
MODEL 14X $6! 



^2**^^ 



^ 









5 

MOBILE 
ANTENNA 

500 watt power rat- 
ing. 10 15-20 40-75 
meters, 

MANUAL SWITCHING 
M0DEL45 




REMOTE CONTROL 
MODEL 55 $95 




MODEL 400 SSB TRANSCEIVER 
5 BANDS 400 WATTS 

includes many deluxe features. Designed to 
use the highly stable, full coverage Model 
410 VFO in fixed station, the miniature 
Model 406 VFO for mobile, or the Model 
405 for MARS operation. 

$420 



12 VOLT DC SUPPLY 

For mobile or portable operation. 
Negative ground standard. Positive 
ground available on special order. 

MODEL 14-117 . $130 



PLUG-IN 
vox UNIT 

for either 
transceiver 

MODEL VX-1 $35 



CRYSTAL 
CALIBRATOR 

KIT $19.50 

SIDEBAND 

SELECTOR 

KIT $18 

Kits for Model 350 
only. Model 400 in- 
cludes these features. 



EAKS YOUR LANGUAGE 

ASK THE HAM WHO OWNS ONE 



LOOK TO SWAN ELECTRONICS 

See the Complete Swan Line at Your Dealers Today: 






MARS OSCILLATOR 

Five crystal controlled channels with vernier 

frequency controL May be used directly with 
Model 400 Transceiver or with Model 350 
and Model 22 adaptor 

MODEL 405X, less crystals $45 




«it- 




DUAL VFO 
ADAPTOR 

Provides for the addi- 
tion of second VFO for 
separate control of 
transmit and; receive 
frequencies. May be 
plugged into either 350 
or 400 transceiver 

MODEL 22 ... $25 



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MODEL 406B : $75 

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For trunk mounting of transceiver. 

MODEL RC2 $25 



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MODEL 250 6 METER SSB TRANSCEIVEI 

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ELECTRONICS CORP. 

Oceanside. CaNfornia 






1 



■^iw^"flw 



P™!^!W^^-^ 



^^•m—mtrniwmnmim* 



— TTn-mTiT-i - I ■ pM ■■III !■ 











* *■"'« '■■ M^t^^^M 



Don Nelson WB2EGZ 
9 Green Ridge Rood 
Ashland, NJ. 08003 



A Poor Man's 220 MHz Rece 



Simplicity wins again uifh this easyto-huild 
receiver for local contacts on the 220 MHz band. 



38 



73 MAGAZINE 



•-mi^ n 




3 TUflMS WO. (B, 1/4 LD,, 

C T ( SEE TEXT I* 

c,i,i5tt itniit JOHNSON WO- 102 WfTH 

I HoiOR a I smTOft 

^ — ^ ' ' — tr 



( 



k i^U 



) 



i.4 K>0|^ 
MILLER 560 



TueULAR 



ALL CARftClTORS DISC CEftAMiC UNLESS OTHERWISE NOTED 
^TUBULAR CEFUMIC 
CHASSS IS GUO C8-A25 

Fig. 1 . A Poor Man's 220 MHz Receiver. This re- 
ceiver is suitoble for use wfth ony simple audio 




OR SOOlt ALPDO POT 
fSEE TEXT J 



6^V 



^SO 



amplifier or ft may be integrated with the Poor 
Man's Transmitter in the August 73. 



In the August 73, I left tlie realm of sophis- 
tication to describe a simple, low power 220 
MHz transmitter whicli has enjojed a remark- 
able performance record- Here is the com- 
panion receiver— a two tube superregenerative 
unit which may be constructed on the same 
chassis as the transmitter. Perhaps you would 
prefer to Hsten to 220 before building a trans- 
mitter. In that case, try this inexpensive re- 
ceiver with any small audio amplifier. 

The "superregen** has a few disadvantages 



on lI crowded band, but crowds are rare on 
220. On the east coast, DX^ers congregate 
near 220 MHz with local club activity at 
220,5 MHz and 221.4 MHz. This receiver will 
easily separate the major frequencies. A 
grounded grid preamplifier serves to increase 
the sensitivity of the rec^eiver, and mini- 
mizes detector radiation to the antenna. The 
groimded grid configuration has the advantage 
of miMimizing overload iirobltrns if you live 
near a high power transmitter (such as T\^ or 




Underside of the Poor Man's 220 MHz Receiver* 
As you can see, construction is very simple. This 



receiver was built as a unit, but it's eosv to buitd 
the circuit into the transmitter. 



OCTOBER 1966 



39 






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MATERIAL IS 
FLASNtNG COPPER 

A* NO-Ef DRILL 
8- 5/32 D(A. 

C- t/4^ ■ 

E- i/a** 



TOP VIEW 













. 1 


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END VIEW 



Fig* 2. Layout of the 220 MHz receiver. H size. 

another 220 ham station). A Nuvistor tetrode 
detector from K6CJN in the June '63, 73 is 
still a fine performer at 220, gi\ ing \ ery good 

selectivity. 

■I 

Thin copper is recommended for chassis 
materia] if it is available, but this receiver was 
breadboarded on aluminum with satisfactory 
performance. The regeneration contiol was 
mounted on the front panel wiUi the tuning 
contrdL One might prefer a vohime cnr^trol 
in front with the regen control on the rear. 
This is not critical so long as the screen by- 
pass capacitor is located at the tube. An 
adapter must he made to use a %" knob with 
the tuning capacitor. This is most easily ac- 
compHshed witli a short piece of Ji'' copper 
tubing. Careful work, short leads and good 
solder joints wiD pay dividends— Take your 
time! 

Witli the tube heaters on, adjust C^ to res- 
onate Li at 221 MHz using a grid dip meter. 
Next, close the plates of C^, the tuning capac- 
itor, and tune C^q to resonate Lg at 218 MHz. 
Values have been chosen to cover timing from 
218 to 228 MHz. Final adjustments should be 
made while receiving a weak signal- 
Correct operation of a superregenerative re- 
ceiver is dependent on the couph'ng of the 
tuning tank (L^, C9) to the preceeding stage. 
Superregeneration might be called partial os- 
cillation—as such it is dependent on a correct 
amount of feedback. 

The trick to making a useful superregener- 
ative receiver is to keep the regeneration con- 
stant over the entire tuning range* This is 
done by selecting the correct point on the 
coil (L2) for the tap. Tlie point farthest from 



ground at which regeneration is constant is 
the most desirable. This is a critical adjust- 
mant w^hich makes the difference between a 
winner and '^anotlier old dog from a maga- 
zine/* In this receiver it is practical to tap 
both Li and L2 at the same approximate 
points^ but small adjustments to perfection 
need only be made in the tap of L2, 

You may notice that the tuning of L^ is 
changed by adjustmmt of C9 because of tlie 
capacitive coupling between tanks. Such cou- 
pling in no way degrades the performance of 
the receiver and was found to be the most 
stable circuit of sev^eral circuits which were 
tried, Selecti\^ty may be broadened by reduc- 
ing the value of R5 to 1 megohm. At liie same 
time, sensitivity^ ^vill be increased* Selection of 
R-/s value will ^ ary with the amount of activ- 
ity in yom* area, and to some degree, individ- 
ual taste. 

Happiness is listening to 220. Gene 
(WB2CVF) breadboarded the receiver and 
had it working in one Sunday, W'ith slightly 
less talent applied to the second unit, the 
author's receiver was performing perfectly 
after three weeks of spare time and a little 
help from Gene. Not all was grim, however* 
A few bugs in the original design were ex- 
terminated in the second unit- Hopefully, you 
will find the project to be a pleasant task for 
several evenings. With the help of a good an- 
tenna, reliable 25 mile reception is no problem. 

The author wishes to thank Steve Wojcik 
for the photographv. 

... WB2EGZ 




KQTES 

S2 IS A 5- POLE 2-P0SiTtC« STEATITE WtF^R 

smrm tsHCwm m transmit positkx^i 

RECEIVER HEATERS AftE QH AT ALL TIMES 



R7 
(RCVRI 

CHAWGE TO 50Ofc POT. 
\/Z IZAX7 



S2-C 



SZ-Q 




y\ 



I C2I 
(XMTR} 



REMOVE S2-S i WAKE 
.PeiMNC^T C0M4EtTlQN 



L5 0CMTR} 



SPKR 



CI tftCVRJ 



L4UMTftJ 




S2-D 



0A2 



TO 
I2BY7 



Fig. 3, Breok-in schematic for operoting the re- 
ceiver with the Poor Man's 220 Transmitter. 



40 



73 MAGAZINE 



DO YOU WANT TO BE ONE OF THE TOP STATIONS 

ON THE FREQUENCY, 

getting a quick response to ail your calls? 

IF YOU DO, WHY NOT TREAT YOURSELF TO SOMETHING 

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THOSE ELUSIVE DX STATIONS REALLY 

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CONCENTRATES your transmitter's tolk-power into o 
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RECOMMENDATION For good operating procedure: 
AJways use minimum bandwidth consistent with good 
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of transmission being employed. THEREFORE^ the 



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MAY BE USED optionally as a bosic SSB generotorl 
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L. E. BABCOCK ft COMPANY 

28 Durant Avenue 
Maynard, Mass. 01754 



OCTOBER 1966 



41 





Larry Will K3ADS 
Overbrook Golf Club 
Bryn Mowr, Pa. 



Amateur Television 

Lets Get Started: Part 

Been thinking of getting on ham TV? This article 
explains how with all the information you need. 



Many is the amateur who has started in 
amateur television only to be frustrated by 
poor results. There have been many articles 
over the years on individual wstems/ but little 
information available to the amateur on setting 
up a complete system and maldng it work* In 
these two articles, the author attempts to re- 
late his experiences with the hope of answer- 
ing some of the many questions on the adjust- 
ment of die TV system. 

First, let us review some of the terms used 
in television work. 



Video: That portion of the television signal 
containing the picture information. (Fig/l). 
Synchronization or sync: That portion of the 
signal containing the timing pulses used to 
lock the monitor to the camera. 
Blanking: That portion of the picture used to 
determine picture edges. 
Set-up: The point of reference blauk. Setup is 
nominally 7,5 per cent of the 100 units atotted 
to the picture. 

Composite television signal: A TV signal con- 
taining all of the above. 



42 



71 MAGAZINE 



PEAK 

WHITE 




sntc 

P£AK 



Fig. 1, Port of the stondord TV signal. This draw- 
ing shows a horizontal sync pulse and video afong 
with the standard IRE reference scale, 

Resolution: The abiKty to detect detail Hori- 
zontal resohition is measured by use of vertical 
lines and is determined by the number of 
\ertical lines that can be seen in tliree fourths 
the picture ^vidth. Vertfcal resoluHon is 
measuied with horizontal lines and is limited 
to a maximum of 525 due to die fact that 525 
lines are the nimiber sent by the scanning sys- 
tem. If interlace is not used, the resolution is 
limited to about 250 lines, Tliis is because 
tlie two fields which are composed of every 
other horizontal line are not precisely locked 
together. Normally, the amateur does not use 
interlace so the amateur signal comes under 
the 250 line category. 

Bandwidth: The total spectrum needed to 
send a television signal Bandwidth is related 
to horizontal resolution by a factor of 80 lines 
per megahertz. More on this when we discuss 
modulators and modulated amplifiers. 
Scan Unearity: The ability to reproduce all 
parts of the picture in correct proportions, 
Aji example of poor vertical Hnearity is the 
stretched heads on a TV receiver caused by 
improper adjustment of the vertical linearity 
control Most amateur cameras have no pro- 
visions for adjusting linearity per se, but do 
have height and width adjustments. These 




should be set for a width to height ratio of 
four to three- 

Luminance hnearity: The ability to reproduce 
all shades of grey from black to wliite cor- 
rectly* 

Ringing: An effect on the picture producing 
multiple images on either side of the main 
object; caused by overpeaked video amplifiers 
in the camera system. This is a high frequency 
distortion in the range above one megahertz. 
Ghosting: Similar to ringing, except occurring 
only to the right side of the main object^ and 
caused by improperly terminated coax lines, 
either video or rf, or by multipath reception 
wlien seen on an off-the-air signal 
Streaking: An effect producing a smear on the 
right side of an object extending for consider- 
able distance^ often to the end of the picture. 
A good example is often seen when white 
names are flashed on a relatively dark picture 
such as during the credits rolling by at the 
end of a commercial program. Caused by dis- 
torticm at frequencies arovmd 15-45 kHz and 
dilBcult to correct. 

Smearing: An effect similar to streaking, but 
occurring over the whole picture giving the 
whole picture a muddy look* Also caused by 
low frequency distortion usually below 100 
kHz. The effects of some of these distortions 
will be covered later. 

Figs. 2 and 3 show the composite television 
signal at the vertical and horizontal rates re- 
spectively. Both traces are useful in signal 
analysis. The video, sjnc, set-up, and blanking 
are shown. Also note the scale used. This is 
the IRE^ standard scale used to measure rela- 
tive amplitudes of portions of the signal. The 
complete waveform equals 140 IRE units. 
Note that zero reference is at blanking. The 
sync occupies 40 units, set-up is 7,5 plus or 
minus 2.5 units and the video is nominally 
92,5 units of information. The whole 140 units 




Fig. 2, Standard TV signal Scope sweep 30 Hz 
amplitude one volt- The blank interval in the cen- 
ter is vertical blanking. Ten corresponds to 100 

IRE units on the scote. 



Frg, 3, Standard television Sfgnal-horizontal. Scope 
sweep 7875 Hz. Horizontal sync and blanking ore 
clearly evident. Note also that the block parts of 
the picture extend down to almost plus 7.5 IRE 
units. 



OCTOBER 1966 



43 



m 




Fig. 4, High Set-up. Note blacks only extend down 
to plus 45 IRE units. The Camera video gain is too 
low. This results in a washed out picture, 

correspuiid to one M>It peat to peak- The 
blackest blacks occur at plus 7.5 units while 
the whitest whites occur at plus 100 units. 
Varying shades of grey occur between these 
limits. If a picture has no blacks, the peaks 
of the video would not extend down to plus 
7,5* Fig» 4 shows a video signal vdth such a 
condition. Here note tlie liigh set-up'. This is 
a normal signal if the picture corresponding 
to this scope trace had no blacks. If, upon 
knowing that the picture contained actual 
blacks, this scope pattern would indicate that 
video gain is too low and set-up is too high. 
Most amateur cameras have no provision for 
adjusting set-up, but do have provisions for 
adjusting gain, A camera with too little video 
gain will normally appeai' like Fig. 4, having 
the appearance of too high a set-up. The cam- 
era gain should be adjusted, when on a picture 
with whites and blacks such lliat the blackest 
blacks extend down to plus 7.5 IRE units. 
While it is desirable to keep the camera out- 
put at one volt, what is more important is the 
correct sync to video ratio of four to 9,25 as 
shown in Figs, 2 and 3, Since most cameras 
have no control over syne gain, the nominal 
4 to 10 ratio should be maintained in prefer- 



TCf^MirtATE 
IN 75 Jt, 



POOV 



m T5a 




-^zna 



F^LJlTE FOLLOWER 



CATHODC fOLLOWe« 



ence to maintaining the output at one volt. 
Adjust the camera to obtain pictures as close 
as possible to Figs. 1, 2, and 3, 

Test equipment 

In order to make adjustments to the TV 
system, some test equipment is a must. We 
have already made reference to the scope. 
This is the most important item. Most any 
scope will do, but the higher priced wide-band 
units are best. In addition, acquire a good pic- 
ture monitor (TV set). In order to view tlie 
picture before it goes through the transmitter, 
a means of tying the monitor and camera 
together must be employed. The biggest prob- 
lem is polarity of the video. The standard 
method of running \ddeo around the shack is 
lilack negative* as shown on all the scope 
waveforms in tins article* You should check 
your particular camera to see if the output is 
black negative and also to see if the output is 
low impedance, specifically 75 ohms. If both 
of these criteria are met, good* If not. Fig* 5 
shows the answer. Both circuits will make the 
camera low impedance, but the cathode fol- 
lower should be used if the polarity of your 
high Z output camera is correct. If you find 
the blacks and sync positive going, use the 
plate follower circuit. This will invert the 
signal and provide the necessary low imped- 
ance output* Both of these circuits will enable 
vou to use several hundred feet of camera 

cable- 
Now that the camera has a low impedance 
output, additional equipment can be hung on 
as in Fig. 6. Note that the cable is terminated 
only once in 75 ohms at the end. All equip- 
ment including monitors and the modulator 
should be looped through' making one con- 
tinuous line- Avoid tee connections. These 
will introduce ghosts even with the line 
matched. At K3ADS, the modulator has the 
75 ohm termination built in so this unit is at 
tlie end of the line. 

In order to make this low impedance signal 
useful in the TV set, a circuit is needed to 
bridge the camera output cable. Fig. 7 shows 
a simple video amplifier that can be mounted 
in the TV set. Power can come from the set. 
Take the output and probe around in the video 
amplifiers to find a point where the picture 



CAMERA 



MONtTOR 
NO, 




^^^■^^ 



Fig* 5- Camera output stoges 



Fig, 6. 'Looping Thru' method of tying several 
equipments together on one video line* 



44 



73 MAGAZINI 





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VANGUARD LABS 



Deph H 

196-23 Jomatca Ave. 

Hellio, NT. 11423 






OCTOBER 1966 



45 



J I 




CAU& 

etc. 

.4Ti*F 400V 





C2 
,47*«F 400V 



F 



TO TV 
OV^O AMP 



Lt 

PEAKING COIL 



R3 
211 



+ leo-aso 



Fig, 7- TV set video preomp. Most TV sets need 
additional ampltfication for satisfactory results 
from one volt of video. 

comes out in the conect polarit>% Most of the 
older sets contain two video amplifier stages 
so it should be possible to find a point with 
sufficient gain to get a contrasty picture of the 
correct polarity. If not, use an additional stage 
to reverse the polarity. The plate resistors are 
of low value to improve frequency response 
and consequently, the gain of each stage is 
low. Now that the monitor is connected, the 
camera perfomiance can be evaluatedi 

Test patterns and tlieir uses 

There are two popular test patterns avail* 
able to the amateur. One is the familiar In- 
dianhead pattern and the other the EIA^ 
pattern. Fig. 8. The EI A pattern is preferred 
since it has ten shades of grey as compared 
to five on the Indianhead, biit either are satis- 
factory. For those using one of the ATJ series 
cameras with a slide profector, these patterns 
are available as slides.* 

Set up the camera facing the pattern and 
adjust the controls to obtain a picture- Adjust 
beam^ target, focus^ and gain for as good a 
picture as possible and tlien check to see that 
the camera "sees' the complete pattern exactly. 
Adjust the camera height and width for the 
proper four to three aspect ratio as seen on a 
properly adjusted monitor* The monitor can 





;t.." 



' I 

■ I i'' I' ' ' 

^;-;-:|- ::H, i 

■ 11 1 i I Ml 
■ -1 




Fig, 9. 60 Hz hum scope at 30 Hz sweep. 120 Hz 
hum will have twice os many alternations. This 
amount is severe. Any hum over 10 IRE units is 

objeGtionoble with levels over 40 IRE units destroy- 
ing the picture. 

be set correctly by getting up early one morn- 
ing and using the test pattern transmitted by 
a local commercial station. If the mom'tor can- 
not be adjusted for a perfect pattern, remem- 
ber the error and adjust the camera for a 
pattern similar to that seen from the commer- 
cial station. This way^ the scanning error often 
present in TV sets can be compensated for. 

On the test pattern^ the horizontal and ver- 
tical wedges are calibrated directly in lines of 
resolution. It should be possible to obtain a 
horizontal resolution of from 200 lines on the 
ATJ series iconoscopes to 300 to 500 lines 
resolution on live vidicon cameras. On vertical 
resolution, the patterns will seem to come 
alive on the horizontal wedges. This pattern, 
called moir6 is caused by the convergence of 
the wedges being nearly parallel to the scan- 
ning Knes* This is an optical effect and should 
be ignored. 

Other troubles 

Fig- 9 shows the effect of hum. Tliis is best 
observed with the scope looking at the verti- 
cal information. The ripples appear on the 
waveform monitor while horizontal bars ap- 
pear on the picture momtor. In severe cases, 
the picture will gyrate with the hum. One 
black and one white bar indicate 60 Hz hum. 



£J2, OR 24 VAC 
.FIUVMENT WINDING 




TO 
/ GRi£i OF 
^VERT, 



OSC. 



CRI 1N3^»ETC. 
tCLlPPERJ 



ADJUST wajue F0« 

BEST FESULTS 



Fig. 8, El A test pot tern 



Fig. 10- Vertical oscillator line lock circuit, 



46 



73 MAGAZINE 




Fig. 1 L Clomping failure. In amateur equipment-, 
usually caused by defective coupling capacitors, 

wliile two pairs indicate 120 Hz trouble. The 
former is caused by poor gromid.s between tlie 
camera, monitor, modiilatorj and other equip- 
ment. Also this hum can be caused by heater 
to cathode shorts in video amplifiers or by de- 
fective power supplies using half wave recti- 
fication, 120 Hz hum is ahvavs caused bv 
defective full wave power supplies. Use plenty 
of filtering. 80 to 100 \kF capacitors should be 
used whenever possible. To further minimize 
this effect^ be sure the vertical oscillator in the 
camera is locked to the power line. Fig, 10 
shows a simple circuit which can be used* 

Another problem occurring often is distorted 
vertical blanking as shown in Fig. II, This is 
often caused by defectiv e coupling capacitors 
in video amplifiers such as C3 in Fig, 5. Bad 
tubes also can cause tiiis defect. Use the scope 
here to locate the defective stage by starting 
at the output and working back. 

Most amateur cameras use free running 
horizontal oscillators. In order to get this oscil- 
lator close to conmiercial standiuds, lock in a 
commercial signal on the monitor, then switch 
to tlie local signal If the horizontal oscillator 
in the receiver goes out of sync, adjust the 
horizontal osciUalor in the camera until the 
picture stays locked in ^when switching back 
and forth between the commercial station 
and the local signal. 

The off-the-air receiver 

In order lo check the operation of the TV 
transmitter when it is completed and to view 
the signals of other ATV stations, a 440 MHz 
receiver is needed. As a starter a modified 
UIIF-TV converter can be used. Avoid modi- 
f\'ing all-channel receivers. While these work 
fine for UHF T\', they do not have built in 
trimmer capacitors in most cases, making 
tracking diflRcult and almost impossible after 
conversion. Whatever converter you use, be 
sure it has an if amplifier. If transistorized, 



care must be taken to insm'e the rf from your 
own transmitter does not burn out the transis- 
tors in the converter,^ 

A popular converter fur ATV is a modified 
Blonder-Tongue BTU-2 series. These use low 
noise diodes and 6ER5 frame grid tubes in if. 
A method of conversion suggested by K3KFL 
is to solder sniidl two-turn gimmicks across 
the oscillator and preselector truamer piston 
capacitors. Use number 20 plastic coated 
hookup wire for this. On late model Blonder 
Tongue unitSj the trimmer on the oscillator 
has been eliminated. In these units, remove 
the cover over the 6AF4A tube socket and 
solder the gimmick across the one already un- 
der the cover. Using a weak UHF-TV station, 
UHF signal generator, or regular 432 MHz 
amateur station, adjust the oscillator to cover 
from about 435 MHz up and careftiJhj adfust 
the preselectors for best signal to noise. In 
addition to the above types of stations, radar- 
like signals and two way communications sta- 
tions may be heard. If these are steady, they 
may be used for alignment. With care, the 
converter will still have high gain and good 
tracking up thru channel 50 or 60 and can 
still be used for UHF-T\^ reception. 

When the system is completed and satisfac- 
tory pictures are being sent and received, then 
it is time to thiiik of a good low-nuise and^ in 
this age, transistorized converter for 440* 
However adequate results can be had with a 
UHF converter and I suggest leaving the high 
sensitivity converter a project until alter com- 
pletion of the transmitter. Good rf amplifiers 
make an improvement over the UHF con- 
verter but because of the wide bandwidtli of 
the TV receiver, tbe impro^^ement is not as 
drastic as that observed on a phone signaL 

Nexth month, we'll cover modulators, the 
modulated amplifier, and antenna systems. 
Meanwliile dig out the camera again. See you 
on 440. 

1. Kai<»er, "A UHF Television Transmitter**, CQ^ April 
1 9 62. 

Daskam, "% Meter TV*\ 73, Match 1964. 
Kennedy-Colby, "The ARC 26 TV TransmitteT^*, 73, 
June 1963. 

Hutton, "Amateur TV Transmitter", 73, March, 1963, 
Taylor, "NSTC Signal for Ham T\r\ 78, January 1963. 
Haines, '^What's A Vidicon", 73, Sept. 1962. 

a, IRE Seal© (IEEE) IRE Standard 23.SI, and the 
recommendations of the Joint Committee of TV Broad- 
casters and Manufacturers for Coordination of Video 
Levels. 

3. EL\-Electronic Industries Association. Standard Tast 
Pattern adopted in 1956. 

4. Test patterns are available from Denson Electronics, 
Bockville, Conn. 

5* Jones, **432 MHz Transistor Converter", 73, June 1966. 
Reference; Television Signal Analysis. Second Edition, 
American Telephone and Telegraph Company, Xxing 
lines Department 1963* 



OCTOBER ]U6 



4T 



E. R. Dovisson K9VXL 
83 Crestview Drive 
Greenwood, Indiana 



The Multical 

A many-use^ many-frequency crystal caUbraior. 



What is the ^'Multical*? As liie name im- 
plieSj **niulti" would suggest several uses, and 
''cal" might infer a calibrator of some sort- 
Well, thafs right, but there is slightly more 
significance to the name. "Multi" is 'also a 
short form term used to describe flip-flop cir- 
cuits known as multivibrators. 

By combining the basic characteristics of a 
free-running multivibrator (astable) with crys- 
tal control, you have a simple, stable, virtually- 
insensitive-to-temperature'Changes, crystal cali- 
bra tor for that receiver you have been wonder- 
ing about. 

Tlie circuit uses no inductors and depends 
upon the crystal for the proper feedback for 
oscillations. Temperature stabiBty is partially 
due to the absence of capacitors. 

Transistor stage Q2 operates with unity gain, 
whereas transistor Qi operates at considerably 
more gain* Both stages are operating as feed- 
back amplifiers. The harmomc generator diode 
Dj is a IN 128, Any general purpose diode 
may be used. 

By using the multivibrator circuit, the wave- 
form obtained is comparatively rich in har- 
monics and could be used without any further 
refinements. However, to insure useful har- 
monics through 30 MHz starting from a 100 
kHz crystal, a harmonic generator consisting 
of R^ and D^ shown in Fig, 1 was added. The 
capacitors Ci and C2 are used strictly for 
coupling and have no effect on frequency sta- 
bility. 

Crystals from 100 kHz up to 1 MHz may 
be used in the Multical with no changes. The 




OOUT 



GiStD 





^ 4X- 




OUT 



pa 



O 



(B) 



Fig< 2. Suggested printed circuit board layout for 
the Multical. A gives the copper side, B the com- 
ponent side. A board for the Multical is available 
for $1 from the Harris Company^ 56 E. Moin 
Street, Torrington, Conn. 



Fig. 1, Schematic of the MufHcal, 



circuit will oscillate from voltages as low as 2 
volts and can be operated safely from voltages 
as high as 20 volts. This wide range of voltage 
operation allows the source to be obtained 
from virtually any place. 

Output from tlie cahbrator may be fed di- 
rectly into the receiver's input, or may be 
coupled to a short whip antenna. With a whip 
antenna, close coupling to the receivers input 
may be required at higher frequencies- (Es- 
pecially at the lower voltage levels,) 

For the more ambitious builders. Fig, 2 
sliows the printed circuit board layout for tlie 
Multical* Due to its small physical size 
(1" X 2")* room can probably be found even 
in the most compact of receivers. Fig, 2 A 
shows tlie foil side, and 2B shows the parts 
placement. 

So the next time you wonder about the ac- 
curacy of your receiver cahbration, give this 
simple circuit a try and you'll know for sure. 

m * * T^X^ V >X 1 ^ 



48 



73 MAGAZINE 




knight'kit 

6 and 2-Meter Transceiver Kits 






fwrtts *^«*«*CH*'/* 




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Compact and versatile Ham transceiver for 
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OCTOBER 1966 



49 



Bill Reynolds K2ZEL 
32 Perry Avenue 
Latham, N.Y. 12! 10 



Connectors for Those Surplus 
Coaxial Tubes 



"Tubes I have, sockets I do not have," and 
they v^ant too much money for them* Also 
many of the sockets available in surplus do 
not have the built-in by-pass connectors. My 
problem came up when I wanted to make 
use of some 4X150A, 2C39A, and 2C40 type 
tubes for vlif-uhf ampHfiers and needed con- 
nectors to attach to lie external electrodes 
and sheet by-pass capacitors. As I began work 
on the projects, I remembered an article by 
WB6A0W^ and tried my hand at making 
the connectors as he suggested, I had trouble 
getting the finger stock to stay in place as 
I added them around the ring. I would get 
one positioned and another would slide out 
of place as I soldered the next one in place, 
1 gave this up as a bad job and started 
searching for a better solution. 

In the junk box I found some ten- thou- 
sandths (0.010") shim stock, and while looking 
at it, I came up with this idea for making 
connectors that work as well as the commer- 
cial ones. The process produces a symmetrical 
connector of uniform thickness permitting the 




Fig, L Stock layout for 4X1 50A screen bypass. 



calculation of the capacitance for by-pass pur- 
poses* 

The first few that 1 made were rolled by 
hand, without the Jig described, and were 
not as symmetrical as the later ones but 
worked quite well nevertheless. The con- 
nectors made in the jig were perfect fits and 
more uniform. The steps for making the con- 
nectors from shim stock can be easily dupli- 
cated in your own shack. The jig will require 
the use of a metal lathe, but tlie resulting 
connector is w^orth it. The dimensions for tlie 
fig and connector described here are for a 
screen by-pass connector for a 4X150A tube. 
For other coaxial tubes the dimensions will 
have to be altered accordingly. 

The shim stock is prepared as follows: 

1. Lay out the stock per the dimensions in 
Fig, 1. 

2. Drill out all holes and punch out the 
center with a chassis punch, 

3. Cut slits with a pair of scissors from the 
knock-out to the stop holes to form the fingers, 
(Hull tlie fingers by hand using round nose 
pliers or make yourself the jig-) 

4. Place the stock on the base of the jig, 

5. Force the washer down into place over 
the stock and then remove the washer leaving 
the stock on the base. 

6. Force the top die down over the top of the 
base, 

7. Remove the finished connector and install in 
the ca\it\' or on the socket, 

■r 

The jig is made of steel stock and is tmned 
on a lathe according to the dimensions in Fig. 
2* When turning the wanher be sure to allow 
for the thickness of the stock or it will be diffi- 
cult to remove in step 5, The top die must fit 
very closely or it will not catch tlie fingers 
and roll them properly. Shim stock of ,005" 
and *015" were also tried and it was found 

Bill is a professor of sdetice at ifw State Uni- 
versify of Neto York at Albantj. He's taught 
a mtnUjer of electronics and ham courses, in- 

chidina one on WTEN-TV. 



sa 



73 MAGAZINE 




On the left are the jig base and top, in the center is the jig rrng^ and on the right ore a piece ot stock 
ready to be formed and o finished connector. 



that tlic ,010 stock was the most satisfactory. 

If the connectors are going to be used as 

grid connectors on planer triodes, do not use 




Fig. 2. Cross section of the jig, 



the top die, but use tlie connector as finished 
following the pressing of tlie washer on the 
|ig base in step 5< W'hen using two or more 
tubes in parallel or with common push-pull 
connection, you can make tlie connectar of a 
single plate, laying out both tubes aiid punch- 
ing on the jig twice. The photograph shows a 
finished connector^ the stock lay-out, and the 
jig. The only inherent problem is that a |ig 
must be manufactured for each diameter con- 
nector that vou desire to make, but once the 
jig is made, it may be used forever and supply 
connectors for other members of your club. 
Make some of those vitally needed connectors 
and use those surplus high frecjuency tubes 
that have been gathering dust in the junk box, 
P,S, I don^t own a lathe either. John Kowal- 
chyk, a machinist friend, helped produce the 
first jigs that were made from tlie drawings. 
Later he was able to show^ me ho\\r to set up 
and use the lathe. This permitted me to make 
others myself. Joe Kelly, a fellow teacher, 
made the photograph, 

, . . K2ZEL 

1. Griffin. Frank WB6A0W, "Do -It- Yourself 4X150 
Stickets," VHF Horizons, April 1963. 



n 



OCTOBER 1966 



51 



Fred J. Dietrich W0IFY/8 
97 East Lake view Ave, 
Columbus, Ohio 43202 




DX Vertical 



Here's a simple^ effective antenna 
you can put up in almost no space. 



^ 



The situation was about as impossible as one 
could imagine. The rig was a home-brew 100 
watt cw transmitter with no drive above 20 
meters^ the receiver a none too stable 20 year 
old models the back yard was full of power 
and telephone Unes, the roof was fragile, slick 
slatej the rig was on the second floor, the line 
noise was often greater than S9, and I wanted 
to work DX! To make matters worse, the 
budget wouldn*t allow more than about five 
dollars for an antenna, and being a student 
didn't leave much time for scrounging. 

An important consideration was tliat of size, 
together with selection of the band or bands 
to be worked. Listening on a 67 foot wire that 
ran to a 25 foot high tree in the back yard re- 
vealed that the only two reasonable candidates 
for DX were 20 and 40 meters because of the 
sunspot situation. This wire had been used in 
an end-fed manner with a little DX success on 
40 meters, but the competition from 40 meter 
beams and foreign broadcast stations made 
things pretty tou^. The situation on 20 meters 
was about the same; it worked well for do- 
tnestic contacts, but fell pretty flat when I tried 

to work DX, 

In order to get the best DX coverage, it is 
necessary to put as much of the transmitter 
power as possible into the lowest radiation 
angle possible- This is so because most of the 
reduction in signal strength that takes place on 
an ionospherically reflected wave takes place 
where the wave passes through the lower 
layers of the ionosphere. The lower the radia- 
tion angle of the antenna, the fewer hops it 
takes to go between your QTH and those juicy 
DX locations. Also important is the fact that 
waves which take off at higli radiation angles 



Freil is a research mwciaic for the Ohio State 
Unwersity Antenna Laboratory. He Jms a 
BSEE, MSEE (PurdueX and is working on his 
PhD. 



frequently pass through Ae ionosphere and are 
lost. This J of course, is just wasted power, 

A study of the vertical radiation patterns for 
various horizontal antennas which appear in 
the first part of the ARRL Antenna Book re- 
veals that it is necessary to get a horizontal 
dipole a ha If -wavelength or more high in order 
that the radiation angle be reasonably low. It 
is also important to notice that even if the an- 
tenna is fairly high, there is usually a good 
deal of radiation in power-wasting high-angle 
lobes. A fairly good compromise is a height of 
five-eighdis wavelength, Tliis gives a radiation 
maximum at about 25 degrees above the hori- 
zon, with something Uke 25 per cent of the 
i:>ower going into high-angle radiation. For 20 
meters, this heiglit comes out to something like 
40 feet, and since tliere was nothing this high 
to attach to, a horizontal dipole seemed not 
too promising. 

The vertical radiation patterns shown for a 
vertical djpole, on the other hand, are much 
more promising- In particular, the pattern for 
a vertical dipole with its center one quarter- 
wave above the ground (this means the lower 
end of the dipole is right next to the giound) 
sliows a radiation pattern maximum at lower 
than ten degrees elevation angle when the 
antemia is located over average, not perfect, 
gromid. There is also no loss of power at high 
angles because there are no extra lobes. This 
seemed to be the answer for working DX with- 
in the limitations of my QTH. A vertical di- 
pole for 40 meters would be 70 feet high, a 
pretty tall order for the $5.00 budget and also 
lor the limited space available for the guys 
which would be required for a mast of this 
height. For 20 meters, the height came out to 
be 33 feet 2 inches for tlie CW band, a height 
which coidd be supported by the house alone. 
The antenna was mounted as shown in Fig. 
1. The support points are the bottom of the 
mast and a point about t\vo-thirds up the mast. 
This has proved adequate in winds up to 50 



52 



73 MAGAZINE 




NOTE -ALL HARPWAftE CA&MlUM PUtTEP OR '^Tfl.fc* pj« ^^^^i * 



OCTOBER 196$ 



5} 




n 



or 60 miles per hoxir, the higliest usually en- 
countered in this location. Since the dipole is 
a full half-vvavelengtli long, it is conventional 
to feed it at the center. This turned out to be 
a rather convenient point in this case> as it fell 
near the height of a window in the second- 
floor shack. I chose to feed it with a gamma 
match to avoid splitting the mast in the center 
and to provide an unbalanced coax feedhne. It 
should work equally well as a vertical doublet. 
The antenna mast itself was assembled 
from various pieces of scrap altiminum tubing 
which were purchased during one morning's 
scrounging. If nice, long sections of telescop- 
ing tubing are available, by all means use 
them; I wasn't so lucky, but 1 still got the 
thing put together. In my particular one, tlie 
bottom 10 feet is a piece of one inch alumi- 
num conduit, the center section is a two sec- 
tion thinwall aluminum T\'^ mast about 13 feet 
long, tlie next section is a discarded TV an- 
tenna boom with the elements removed, and 
the remainder of the 33 foot 2 inch length is 
made up of two pieces of aluminum tubing 
scrap. Tliis length was found from the equa- 
tion L = 468/f(MHz) where L is in feet 

Since the tubing didn*t telescope together 
nicely, it was necessary to devise some means 
of fastening them together. This was accom- 
plished by squeezing the larger of the two 
tubes for a particular joint in a vise until it was 
narrow enough to provide a tight fit for the 
smaller tube. The joint was then bolted with 
two bolts about six inches apart through both 
tubes. Fig, 2 illustrates the method. All the 
joints were taped vdth plastic electrical tape 
after tliey were assembled to keep moisture 
out Cadmium plated haidwaie was used 
ever>^vhere to prevent corrosion and rust. 
Stainless steel hardware would be even better, 
but I have seen no signs of rust after two 
years with the hardware I used- 
Fig- 3 sliows the details of the gamma feed 
arrangement. The gamma tube is fed from the 
center conductor of the coax through a 33 pF 
variable capacitor which is enclosed in a plastic 
refrigerator jar to protect it from tbe weather. 
It is important to drill a small hole in the bot- 
tom of the jar to allow condensation to drain 
out I learned this the hard way. I didn't pro- 
vide a hole, and after about 6 months of op- 
eration there was about a lialf inch of water 
standing in the bottom of the jar. Changes in 
barometric pressure cause tlie jar to **breathe*' 
humidity inside* The top of the far is removed 
to adjust the capacitor during initial tuning. 
Once it is tuned ^ the lid is snapped back in 
place- The jar attadied to the wooden dowel 
with a long 6-32 screw which passes through 
the dowel, through the jar, and screws into one 



of the mounling holes of the variable capacitor. 
This joint was sealed with mastic cement be- 
tween the jar and tlie dowel to prevent rain 
from entering the Jar at tins point. 

The gamma tube is supported on the bottom 
by being set into a hole drilled partwa>' 
through the doweL This should be of such a 
size to provide a snug fit for the tube. A small 
hole, concentric with the large one, was drilled 
entiiely through the dowel to allow rain to pass 
freely through the gamma tube and out tlie 
bottom. The electrical connection is made at 
the bottom of the tube by means of a clamp 
made from scrap sheet aluminum and fastened 
with a 6-32 machine screw which also holds 
the solder lug for tlie wire from the capacitor. 
This joint was taped after completion of the 
antenna. The top clamp is shown in Fig, 4, 
and consists merely of a piece of sheet alumi- 
num formed into clamps at both ends. 

Fig. 5 and 6 show the details of mountingp 
The long ceramic insulators shown happened 
tu be on hand; probably something smaller m 
size would be adequate. The mast turned out 
to be only about three feet from tlie wall of 
the house. A larger spacing would be desirable 
from the standpoint of efficiency, but the prop- 
erty line prevented it 

Adjustment of the gamma match proceeded 
as follows* Tlie transmitter frequency was set 
to the center of the desired frequency range 
(in my case it was 14050 kHz) and the output 
power was adjusted for the minimum required 
to give full-scale deflection on the SWR meter, 
(An SWR meter or impedance bridge^ is essen- 
tial for the proper tuning of any antenna sys- 
tem.) If possible, choose a time when the band 
is dead so as to cause a mimmum of interfer- 
ence. Before kej^ing the transmitter, set the 
top gamma tube clamf) to some position, say 6 
feet above the center of tlie antenna, and 
tighten it, (now take your hands off tlie thing!) 
Key the transmitter and adjust the variable 
capacitor until the standing wave ratio 
is minimum. If the reading at minimum is too 
high, move the clamp up or dowoi a few inches 
and repeat the procedure. K this improves the 
SWR, move the clamp again in the same direc- 
tion. If the SWR goes up, move the clamp in 
the opposite direction. If the SWR carmot be 
brou^t to a satisfactory level, it might be nec- 
essary to move the center clamp on the an- 
tenna up or down a few inches. The part of 
the antenna w^hich is close to the wall of the 
house will be somewhat detuned by the house, 
and the electrical center of the antenna might 
not be located at the exact mechanical center. 
It should be possible to get tlie SWR down to 

K Kyle, Jim, ^'B.F. Measurenients,** 73, Dec, 1965, p. 20, 



54 



73 MAGAZINE 



1 to 1 at the center frequency; I quit when I 
hit 1,25 to L It stays below 1,75 to 1 any- 
where in the CW band^ which is entirely satis- 
factory for all but the most touchy transmitter 
pi-network. 

The tuning was accomplished by having one 
man on aii extension ladder and the other at 
the rig. Since the total feed line length for my 
installation was only seven feet, and tlie win- 
dow it passed through was left open during the 
tuning procedure, there was no problem of 
commvmication between the man at the rig 
and the man on the ladder, 

A convenient feature of this antenna is the 
ease with which it may be lowered for inspec- 
tion and repair. It is necessary only to remove 
one screv\^ from the upper insulator, disconnect 
the feed line from the transmitter^ tie a stioug 
cord to it abo\^e the center, and lower away, 
I am able to do this from inside the shack by 
opening the upper half of the window. To 
raise it, it is necessary to have someone posi- 
tion the bottom of the mast over tlie bottom 
cone insulator and hold it there while I raise it 
back to a vertical position. The XYL performs 
this task admirably. 

A note about radials. One of the reasons for 
selecting this type antenna is that it is center 
fed and does not require radials for efficient 
opera don. The more popular vertical is a 
quarter-wave type which must be fed against 
a radial system or some other form of ground. 
The reason that many of these fail to live up 
to their expectations is because of an inade- 
quate counterpoise- A single ground rod at the 
base of a quarter-wave antenna is usually not 
adequate. I know; I've tried it with disastrous 
results! The transmitter power is dissipated in 
large ground resistance which results from a 
poor groxmd. A good system of buried radials 
is excellent for a quarter-wave vertical, and a 
system of radials above ground for the popu- 
lar ground plane antenna works well- I did not 
have room near or in the ground, and the 
fragile roof and a landlord who discouraged me 
from walking on it pre\eivted the erection of 
anytliing od the rooL 

I did try stringing some radials in the base- 
ment and feeding the whole mast against these 
for 40 meter operation using a variation of the 
bazooka balun feed, but that's another story. 

On the air results have been very encourag- 
ing in the relatively little operating time I've 
had available. A check m the log shows mostly 
569 and 579 reports out of Europe and 589 s 
out of Central and South America. Since I am 
restricted to Saturday morning operation, I 
don't usuallv hear the Asian and Pacific sta- 

tions. 

. . . W0IFY/8 



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73 MAGAZINE 




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Jim Kyle K5JKX 
1 236 NE 44th St. 
Oklahoma City, Okia 



An AC Voltbox 



\ 



Does the line voltage tend to wander about 
a bit at your QTH? Or are you checking out 
new gear and needing a way to simulate high 
or low line-voltage conditions? 

One way out of these (and all similar) 
problems is to buy an adfiastable autotrans- 
former. General Radio calls them **Variacs" 
and other people have other names for the 
gadgets, but they're not too unfamiliar. 

However, they are expensive. In sizes rated 
for any power capability at all, they begin to 
make sizable dents in the region of the pocket- 
book. Even in surplus! 

Another way out of the problem is to build 
yourself a voltbox. It won't have quite the 
flexibility of the variable transformer, but on 
the other hand it won*t cost nearly as much 
either. In fact^ you can build a stripped ver- 
sion out of most anybody's junkbox. 

The trick of hooking up a low-voltage trans- 
former so that its secondary is in series with 
the line voltage is as old as the hills. It must 
even have had whiskers when Signore Mar- 
coni tapped out his famous three dits* And 
that's the basis of the voltbox. 




-;;— 5-POSlTlON J 



Fig, 1, Schematic diagram for voltbox. Tl con be 
any filament transformer. Power capacity of volt- 
box will be product of transformer secondary cur* 
rent rating and (line voltage minus secondary 
voltage). F1 should be rated same as secondary of 
Tl. As shown, output voltage will be (line minus 
secondary) ot switch position 1, (line minus half 
secondary) at position 2, straight line at 3, (line 
plus half secondary) at 4, and (fine plus full sec- 
ondary) at 5. If secondary windings happen to be 
reversed in polarity from that shown, only effect 
will be to make position 1 the high end of the 
range and position 5 the low. 



But its a bit more than that. The simple 
series-secondary hookup is fine for either 
boosting or lowering line voltage by a fixed 
amoimt. It even lends itself to use of a dpdt 
switch to take your pick of boost or cut. But 
it*s not much for rapid control. 

By using a center-tapped filament trans- 
fonner, however, and a 2-pole rotary switch 
with 5 positions, it's not too hard to get a sort 
of "active power rheostat" effect. The sche- 
matic shows the hookup. In position 1 of the 
switch, the fuU i^ccondaiy of the transformer 
is in series with the line and out of phase, so 
that if we're using a 10-volt center-tapped 
transformer and have a constant line voltage 
of 1 15 the Voltbox output will be 105 volts at 
this point. 

Position 2 cuts out half the secondary, so 
we have only 5 volts to work with, but retains 
the same phasing. Now we have 110 volts 
out* 

Position 3 eliminates the transformer alto- 
gether for straight through II 5- volt operation. 
Position 4 is the same as position 2 but the 
phase is now such that our 5 volts adds; we 
get 120 volts out. Finally, position 5 adds the 
full 10 volts for 125-voIt output. 

So by the twist of a switch^ we go from 
105 to 125 volts in 5- volt steps. Had we used 
a 25-vQlt center-tapped transformer, the range 
would have been from 90 to 140 volts in 
12M-volt steps. 

The fuse shown in the schematic is for the 
protection of the transformer; the voltmeter 
across tlie output socket is simply a conven- 
ience so that you can monitor output voltage 
constantly. 

Some TV power transformers have double 
6.3-volt secondar>^ windings, with at least one 
of them centertapped, as well as a S-volt rec- 
tifier winding. These can be used to build a 
really wide-range Voltbox; the output steps 
could be arranged as 97.4, 102,4, 108.7, 
111,85, 115 (line), 118.15, 121 A 127.6, and 
132.6. Tliis would require a 9-position 2-pole 
switch. Wiring would follow that of the sche- 
matic except that all secondaries would be 
hooked up in series with the center-tapped 
winding at the bottom of the string and the 
5-volt winding at the top. Measuring second- 
ar>^ voltages from the bottom of the string, 
you would have 3J5^ 6.3, 12,6, and 17,6 volts. 
The bottom connection would go to switch 
position 1 on wafer A and the 17,&-valt end 
would go to positions 1, 2, 3, and 4 on wafer 
B and 6, 7, 8, and 9 on wafer A. Intermediate 
connections would go to 2, 3, and 4 on A 
(in order) wliile positions 1 through 4 on A 
would connect to 6 through 9 on B in the 
same way as 1 and 2 connect to 4 and 5 in 



5« 



73 MAGAZINE 



the schematic; positions 5 on both wafers coo- 
nect together for a straight-through connection. 

In such a hookup, power rating would be 
hmited by the lowest current rating of the 
individual windings. Thus maximum output 
current might not be greater than 600 ma, or 
about 70 watts worth of power at 117 volts. 

In the hookup shown in tlie schematic, 
power rating is equal to the current rating of 
the secondary multiplied by the lmv€st output 
voltage. It will increase at higher output volt- 
ages but this provides you a safety margin. 
Using a 10 -volt S-ainp transformer youll have 
a power rating of more than 500 watts— plenty 
to run any receiver or VFO, and adequate for 
a performance test on much other equipment. 

The same idea can be applied as an input- 
power control for a low-power transmitter, 
since output of a 600-volt power supply can 
be varied over a 1:50- volt range by the 105/ 
125 volt range of the Voltbox. Youll probably 
discover dozens more uses for this handy 
gadget as soon as you have it finished and use 
it for a while! 




^-^•■^■- ^'.- 



Parts Storage 

Cigar boxes are much more satisfactory for 
storing small parts than the plastic drawer 
type cabinets* If you have ever tried to close 
a drawer full of resistors you will know what 
I mean. 

First it is important to stock up on all types 
of cigar boxes. To do this you will probably 
have to get on the cigar store waiting list. 
When you have a suflScient assortment of boxes 
take the ones of the same size for each type of 
component you want to store. Over a period 
of time and with enough shuffling from one 
box to the other, and end result will be a neat 
storage for your small parts, 

. , . Ed Marriner W6BLZ 




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I 



OCTOBER 1964 



59 



Gus Browning W4BPD 
Orangeburg, S.C* 



Gus: Part 16 



Last montli I was on Aldabra Island having 
a ball. After lepairing tbe Teflon needle valve 
with a hot soldering iron and getting my an- 
tennas broadside to the USA and Europe, I 
was all set for the pile-ups, 

I found that there were interesting tilings 
to observe on the islands, I saw the Booby 
birds tiying to battle their way thru with 
their craw full of fish every evening (read 
last month's issue). Or take those coconut 
crabs that invaded the back porch where I 
was operating every night. These are mean 
rascals about twice the size of both of your 
fists when placed together. They just love to 
sneak up on yon at night (they don't come 
out in the daytime), and when you are not 
watching all of a sudden they will take a snip 
at your leg; I mean right up imder your pants 
cuffs* They are always fighting each other; 
usually every morning there were a number 
of dead ones laying around that got killed 
during the night. I think they hate each other 
and think nothing at all about battling to 
their death" at the first sight of another one. 
Sometimes when I awoke by the operating 
position in the morning there even were a 
few dead ones on top of the table* I suppose 
they climbed up on the table via the over- 
hanging table cloth. I guess they would make 
FB house pets if you did not want any of 
your neighbors visiting you. One night I 
caught about 25 of them and placed them 
in a large box so that 1 could take a pictnre 
of thera the next day, but the next morning 
every one of them was dead, I suppose they 
had a real battle royal in that box during the 
night. All of them were snipped up; pieces 
of coconut ciabs were all over the box; not 
a whole one was to be found. 

Another interesting type of nightly visitor 
was some extra large bats. I will teU you of 
my encounter with one of them the very first 
night I was there. My operating table was 
on the back unscreened porch, I had been 
noticing something flitting between me and 
the light bulb a number of times, and thought 
possibly it was a large candle fly or some- 
thing like that. I had a nice pUe-up going, 
operating SSB on 20 meters. Someone had 



just called me and I was about to jot down 
the call sign of the station calling, but all of a 
sudden, something lit on top of my partly 
bald head. This "thing** was straddling my 
headphone band (the mike was also mounted 
from this headphone band ) and its claws were 
dug into my very thin hair and scalp. I yelled 
into the mike, *7^st a minute. Buddy, I got 
some trouble here/* Then I sort of sneaked 
my hand up to my head to feel this thing 
that was on top of it, nice and soft, I quickly 
withdrew my hand from this Httle fur covered 
thing setting on top of my hair. I sort of froM 
up for a minute, and then decided this thing 
had to be removed from my head. I had to 
either do something or else sit there all night. 
I decided to do something and to do it in- 
stantly, I grabbed this thing from my head, 
and threw it on the floor, all in one single 
motion. Down on the floor went the head- 
phone, mike and this thing, which turned 
out to be a large bat having a wing spread 
of about 20 inches. The poor headphone and 
mike really slammed to the floor; I thought 
for sure they were nnned. The bat was out 
cold. I picked up the phones/mike combina- 
tion and listened in, whistled in the mike once 
and discovered it was all OK, I was back in 
business again. Then I said into the mike, 
"Who was that calling me?"— the wrong thing 
to say in a pile-up. Back came about 25 
stations; whoever was calling me on that fre- 
quency was clobbered, I then put a little check 
mark beside the time and report I had alreadv 
entered in tbe log. In the excitement I com- 
pletely forgot ihe call sign of whatever was 
calling me- Sure enough when I got back 
home, I found a QSL card from this fellow 
all filled in with the proper time, date, report, 
etc. He mentioned I had returned to his call 
and that right after I had given him his report 
said, "Wait a minute; I've got troubles " Then 
when these troubles were o^er with he got 
smothered with QRM. I sent him a QSL card, 
I even wrote him a letter telling him what the 
trouble was that I had. I never did have one 
of those bats land on my head after that. I 
sort of learned to live with them from then on. 
At the time I was on Aldabra, the total 



6a 



73 MAGAZINE 



population was about 20 people. There are 
three industries on the island— fishing, copra, 
and catching large sea turtles, Wliich is the 
best money producer I have no idea. Possibly 
it*s the fishing. The fishermen are more afraid 
of the large groper fish than they are of sharks* 
It seems that these gropers sort of sneak up 
on the fishermen (who are in the water spear- 
ing fish), and take a chunk of meat out of 
Iiim now and again. One fellow I met down 
there had the calf of his lower right leg com- 
pletely gone from a groper bile. They told 
me they can usually scare a shark away by 
making lots of commotion in the water. 

The catching of the large sea turtles was 
interesting work to observe. Usually three fel- 
lows go out in one of the large pirogues 
(boats). When a turtle is seen they row the 
boat near tlie turtle, and they throw a spear 
into the back of the turtle j the spear only 
goes into the turtle^s back a few inches. The 
turtle is hauled into the boat^ turned over on 
its back and then a few more are caught. 
When they have a good haul they come ashore 
and the turtles are placed in the turtle pond. 
The spearing of the turtle does him no harm 
since the spot where the spear went thru 
its soft back soon heals over and tlie turtle 
is as good as he ever was. 

Life on Aldabra to me seemed very good; 
everyone had all the food they needed fur I 
l}eheve each one there was allowed one pound 
of rice per day. If they did not use their ration 
the owner of the island bought the rice back 
from them at a fair price, I saw no one beating 
their brains out working tliemselves to death. 
They all seemed to be sort of taking it easy. 
I think they are all very satisfied with their 
job. Of course, occasionally there is a little 
trouble between a few fellows, which the 
island manager soon clears up. There is even 
a small |ail on the island that on occasion is 
occupied, but not ver>^ often, I suppose the 
island manager is the judge in these disputes. 
Life to me on Aldabra was very enjoyable; 
the bands were open nearly around the clock. 
With the sun spot count increasing each day 
noWs 1 certainly would like to return to Alda- 
bra, With even 10 meters starting to open 
again I bet I would have a ball Remember 
when I was down there the sun spot count 
was near the 11 year minimum. The possibiliL) 
of my returning there at this time seems to 
be very remote, if not impossible; but if the 
chance ever turns up I would like to be on 
again from down there. Oh, yes, if yon want 
one of the most delicious meals in the world, 
tr\^ one of the Aldabra turtle steaks. They are 
one of the most tender steaks I have eaten. 




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If you are interested in picking up sea shells 
by ull means go to the Aldabras; they are 
there by the thousands just waiting for some- 
one to pick them up, I sent Peggy two large 
boxes of them. 1 had aheady sent her other 
sea shells from other spots and she told me, 
**No more sea shells, please." One extra large 
clam fossil I found there was large enough 
for me to lay down in and be closed shut. 
We shipped tliis one back to Mahe to be put 
in their museum. The clam from that shell 
would have fed 30 or 40 people^ I guess. Its 
age was estimated to be more than a thousand 
years old. With all the birds, fish, copra, sea 
y^hells, bats, and miles and miles of nice sandy 
sea coast, life there is not bad at all. All the 
workers there are men, so there is never any 
trouble with arguments over some woman. 

I stayed on Aldabra Island for 17 days. I 
found that 17 days is by far too long to stay 
at one QTH as far as DXpeditioning is con- 
cerned. Give me 7 good days and everyone 
will be worked who really tries; after that you 
have to start digging for QSOs. But I was sort 
of stuck for those 17 days, since Jake the boat 
owner had the Kttle Lua-Lua up high on the 
beach, painting and cleaning it up. He put it 
up on high dry sand when the moon was full 
and had to wait until there was the next extra 
high tide so he could float it away again. 
This extra long stay was not too bad, since 
there were many things of interest to do and 
to look at. Time flew by anyway. 

Finally Harvey gave me a call on 20 and 
said for me to be ready to depart the next 
morning at 8:30 AM. Down came the antenna^ 
off went the power plant, things were all 
wrapped up and made ready to load up the 
boat. I contacted the manager of the island 
and told him I would need the use of a 
pirogue the next morning with a few fellows 
to help me load up and row out to the Liia- 
Lua when it arrived. To bed I went for the 
fiist good long night's rest I had since I had 
arrived at Aldabra. I visited all the workers 
and thanked them all lor llieir help, thanked 
the island manager and took one final look 
at the camp site, I was ready to QSY from 
Aldabra at 8:00 AM. 

The Lua-Lua arrived at about 8:15, so out 
we went in the loaded pirogue. The old SE 
monsoon by this time had really got going 
and we had a heck of a time loading the 
eqvn'pment from the pirogue to the Lua-Lua, 
A number of times things nearly went over- 
board, until we got the swing of the w^ay the 
waves were behaving. We would watch for a 
big swell to start our way, and yell to the 
fellows in the Lua-Lua to get all set; then 
we grabbed an arinful of items and waited 



until the swell pushed our pirogue up high, 
parallel with the deck of the Lua-Lua, and in 
a fast swing handed items to the outstretched 
anns of the fellows in the Lua-Lua. This re- 
quired some split second timing and fast move- 
ment on the part of the fellows on both boats. 
The last item to leave the pirogue was me. 
The pirogue departed for the beach, and we 
set sail for Nfahe, 

The seas were in a ver>'' foul mood all the 
way back, I finally managed to get my equip- 
ment mounted on the eating table, the old 
putt-putt fastened down, and I was again 
/MM Quite a number of waves swept com- 
pletely over the ship, and the fellows at the 
wheel hung on for dear life so they would 
not be swept overboard* What a time we had 
trying to shoot the sun, moon, Venus, etc.» 
witli the horizon very vague; locating the hori- 
zon was a must before any bearings could 
be taken. All this time I am at the radio 
listening to WWV or some other station with 
standard time signals, calling ulf the seconds. 
Both Han^ey and Jake had their sextants in 
their hands. Eventually we would get a shot 
and Harvey and Jake w^ould then go to their 
little desks and start trying to figure where 
w^e w^ere! Every now and again they would 
actually agree on the same exact spot. One 
time one of them called out the answers to liis 
shot and according to my map we would have 
been about 300 miles west of Cairo, Egypt, 
out in the Sahara Desert! He later re-figured 
and found that he had subtracted one oi his 
figures instead of adding. But as a mie their 
figLU"es more or less agreed. Dead reckoning 
helped quite a bit also. In plain English, 
dead reckoning means you are located at such 
and such a place using common sense, 

The second day out from Aldabra, on the 
way back to Mahe, I was on the air having 
a FB time QSOing the boys with those break- 
ers breaking over the boat, and bango— the sky 
hght above my operating table was struck by 
an enormous wave^ it was lifted up and about 
a bathtubfull of sea water came on top of me, 
the equipment, cameras and all. This brought 
a sudden silence to the equipment. It was 
sflent all the rest of the way back to Mahe, 
I tried drying it off the best I could with what 
damp clothes we had on deck, but it was a 
long way from being dry. It took us about 10 
days to battle our way back to Mahe; all this 
time the equipment just lay there with the salt 
water doing its worst to it, parts of tlie chassis 
starting to turn green when we arrived on 
Mahe. It did not look good to me at all; I 
thought for sure that 1 wamld have to get 
word to Ack to send me another KWM-2, but 
before I sent out this distress message I de- 



62 



73 MAGAZINE 



p 




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DIPLOMAT- 6 (01-6) 

Available to VHF-DX^RAG CHEWING enthusiasts is another New 
5/8 wave vertical base station antenna the Diplomat ^ 6 
rated for a maximum input of 1000 watts. 

For complete details on this New Line of Antennas Write, 





Cj&^wnicA, Mia 



4610 NORTH LINDBERGH BLVD, 
BRIDGETON, MfSSOURI. 63044 




cided I \^ould try overcoming this salt water 
trooble. 

OJT went the cal)inet^ and the scrubbing 
job began. After two days of hard work, it 
looked very nice and clean. I plugged it in, 
expecting the smoke to rise from somewhere* 
There was no smoke from it, but there were 
no signs of any signals from it either. Nor 
was there any excitation on transit* The only 
tiling that moved was the S meter, and it 
moved backwards. It looked like I was in for 
lots more cleaning before there were going 
to be any signals from VQ9A. This time I 
really dug in. First it got the water hose treat- 
ment! Try squirting water down in those 
pretty httle ij transformers- you will be sur- 
prised the places it squirts out! After a few 
days of this cleaning, wiping, polishing, and 
sponging, things looked very good. This time 
I placed the equipment out in the hot Mahe 
sunshine for two days, turning the chassis 
over every hour; finally on the third day I 
placed it in the oven at the hotels turned the 
heat up to 160 degrees and let it cook for 6 
hours. This time I knew it was dry before I 
plugged it in. Still the S -meter read back- 
wards, and a very faint hum could be heard 
from the phones. On PA plate current position 
the meter read about 15 mils. Stilly no excita* 
tion. This time 1 was ready to send Ack that 



distress message for sure. After some thought 
I decided I would try just once more before 
sending this message to Ack. Tliis time out 
came most of the parts, the ij transformers 
inside were all green^ covered with green scum 
and mildew. Each one was very carefully 
cleaned with carbon-tet; the trimmers were 
taken apart and I noticed the silver plating 
on them was starting to peel off; the power 
transformer was even taken apart and found 
to be covered with this green scum. Sometime 
one of you fellows might try a real cleaning 
job on the little band switches in modem -day 
equipment. Tliis time I spent 3 full days clean- 
ing; then back into the oven again for more 
baking, and then with not much hopes it was 
plugged in* Again the S-meter read back- 
wards—but the receiver was operating again. 
Next I tried the transmitter. By golly, it 
worked I 1 ! 

I was back in business again at VQ9A- I 
could never get the VFO to calibrate right, 
and when I returned the set to Collins about 
two years later, the S-meter was still reading 
backwards. They sent me a new VFO to install 
so the calibration difficulty was eliminated, I 
never did have any more trouble with the 
rig after that, except the usual amount of tube 
trouble. 



* « 



OCTOBER 1966 



«3 



AMATEUR ELECTRONIC SUPPLY 



RECONDITIONED 



EQUIPMENT 



* 10 Day Free Trial [Lose only Shipping Chargesl * 30 Day Guarantee * Fu]l Crertit Within 6 Months on Higher Priced 
New Equipment ^ Pay as Little as $5.00 Down and Take up to 3 Years to Pay the Balance ^ Order Direct from this Ad ! 



AMPLIDYNE 

62) XmiF SI 49 

261 VFO 35 

5100 Xmtr 1 B9 

5I00B Xmir 119 

5tSB'B SSBGen 99 
UIQOOA LiTi/Sup !49 

CENTRAL ELECT. 
lOA Ejiciter S 49 

IDB EKcitcf 69 

20A B^clier (table) 89 
QT'i Ami-Tnp 9 

BC458 VFO 19 

600L Linear 219 

CLEGG 

SQUIRES-SANDERS 

99'er Xcvr S 99 

Thor 6(RF Qfilyl 175 
Thor 6 DC Sup 'n)d 95 
ThflT 6 AC Sup Mod 75 
Zeus Xmtr 375 

Venus Xmtr 2^9 

Venus AC Supply 75 
Ap^jllo Lmear 175 

SS Booster 49 

Intefceptor Rec 295 
22 ©f 2m Xcvf 1^9 

SS I R Receiver 475 

COLLINS 

75A-J Receiver SJ19 

75A-2 Receiver 219 

75A-3 Receivef 269 

75A-4 ^0^*000) 349 

270G Speaker 19 

75S-i Receiver 29S 
75S-i Wattfs Rej. 32S 

75S-3 Receiver 399 

7S5-3B Receiver 475 



75S-3C Receiver 525 

32V J Xmir 199 

32S-1 Xmtr 375 

325-3 Xmtr 495 

625-1 VHF Ccw»v 595 

3I2B-4 Cofisoie 149 

KWS-( tSOO-IDOOl 675 

KWM- 1 (0-500) 249 

3510-1 Mount 25 

KWM*2 Xcvr 750 
K'^r<-2 Waters rej. 775 

35ID-2 Mourn 75 

MP^I Mobile Sup H9 
399B- i OX Adaptof 25 

R. L. DRAKE 

\ A Receiver SI 09 

2 A Receiver 159 

2AC Calibrator 12 

2B Recefver 189 

2eQ Combo 29 

2BS Speaker 9 

TR-3 Xcvr 369 

AC- 3 Supply 65 

DC-3 Supply 95 

R'4 Recetver 279 

R-4A Receiver 299 

MS-4 Speaker 12 
T-4X Transmitief 299 

EICO 

720 Transmitter S 49 

722 VFO 34 

730 Modulator 39 

753 Transceiver 149 

ELMAC 

AF-67 (AS-IS) S 20 

AF-67 Xmtr 4S 

AF-68 Xmtr 79 

PMR^6{AS-IS) 20 

PMR-6A (AS-IS) 25 



PMR-7 Receiver 39 
M 1070 AC DC 39 



GLOBE GALAXY WRL 


Scout 656 Xmcr t 


y34 


Scout 680 Xmtf 


35 


Scout 680 A Xmtr 


39 


LA- Linear 


69 


Scouc Deluxe 


49 


Hi-Bar^der 62 


99 


Chief 90 Xmtr 


29 


Chref 9t)A Xmir 


34 


Cliief Deiy)te Xnycr 


39 


Ktng50GA Xmtr 


225 


King SOOB Xmt. 


249 


DSB'iOO Xmtf 


49 


HG303 Xmtr 


29 


Gataxy 300 Xcvr 


149 


PSA-300C AC Syp 


49 


G.300DC 


6S 


Galaxy V Xcvr 


299 


AC Supply 


59 


Detu>te Console 


69 


RX-2 VFO 


59 


755 VFO 


24 


755A VFO 


29 


ReiectoT 


15 


UH-I Moddatof 


29 


VOX- 10 


5 


MM^iOO Hatcher 


7 


GONSET 




Comm II 6m 


S 49 


Comm IV 2m 


199 


G-28 Xcvr 


149 


GC'IOS 2imXcvr 


169 


900A (2ml Xcvr 


249 


902A DC Supply 


49 


901 A AC Supply 


49 


G*33 Receiver 


44 


GR^2 1 Receiver 


49 



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To: AMATEUR ELECTRONIC SUPPLY 
4828 West Fond du Lac Avenue 
Milwaukee. Wisconsin 53216 ' 

Ship me M following Reconditioned Equipinent: 



FJRST 

CHOICE 



SECOND 
CHOICE 
(!F ANY J 



THIRD 
CHOICE 

{IF ANYJ 



I enclose S. 



I will pay balanced! any) 



□ cod n 1 y^^f D 2 yeafs □ 3 years 



Name. 



Address 



City. 



State 



,Zip 



n Send Reconditioned Equipment Bulletin 



G'43 Receiver 59 

GR-212 Receiver 59 

G^B Receiver 49 

3- way Suppljr 19 

Thin^Pak 19 

G-76 Xcvr 99 

G'76 AC Supply 75 

G 76 DC Supply 75 

G-77 Trarvsmitte-' 49 

G-77A Transmitter 69 

GSB-rtX) Xtmf {69 

G5S-I01 Linear 169 

Super 6 iPS-iSi 10 

Super 1 2 Conv 29 

HALLICRAFTERS 
Sky Buddy Rec S 39 

5-38 B Receiver 24 

S-38E Receiver 34 

S-40B Receiver 49 

S53 Receiver 44 

S^53A Receiver 49 

SX-62 Receiver 125 

SX-71 Receiver 89 

S-76 Receiver 69 

S^77A Rec (AS-IS) B 

S-86 Receiver 59 

S9S ISOMc Rec 39 

SX-96 Receiver 119 

SX-99 Receiver 75 

5X^100 Receiver 139 

SX*!OIMk 11 Rec i2S 

SX-lOmk Ul Kec 139 

SX^IOIA Rec 199 

S^IOB Receiver 69 

SX^ni Receivet 134 

SX-IIS Receiver 325 

SX- 1 17 Receiver 225 

S'I20 Receiver 39 

SX-140 Receiver 69 

CRX-2 150 Mc 69 

CRX*3 Aircraft 69 

R-46 Speaker 8 

R-46B Speaker 9 

R-48 Speaker 12 

HTV|7 (AS-IS) 25 

HT^30 Xmtr 1 19 

HT-31 Linear 119 

HT^32 Xmtr 249 

HT^32B Xmtr 349 

HT03 Linear 169 
HT-33A tctmv to 8j 269 

HT-37 Xmtr 225 

HT.40 Xmtr 49 

HT'44 Xcvr 249 

P-26 Supply 49 

P^ISOAC Supply 75 

P' 1 50DC Supply 75 

SR.t60 Xcvr 189 

HA.5 VFO 4S 

HA*6 Transverter 89 

HA- 10 Tuner 15 

HAhMARLUND 

HQ-mOC Rec 5109 

HQIIO Receiver 119 

HQ-MOC Rec 129 

HQ-nOA Rec 159 

HQ-120 Receiver 59 

HQ-129X (AS-IS) 25 

HQ-140X Rec 99 

HQ-145XC Rec 169 

^10-160 Receiver 189 

HQ-I70 Receiver 169 

HQ-I70C Rec 179 

HQ-I70A Rec 239 

HQ-170AC Rec 249 
HQ-l70ACwith 

immunizer 299 

HQ-iaOC Rec 249 

SP-6O0JX.I7 Rec 275 

HX-SO Xmtf 199 



HEATHKIT 

HR-20 Receive^ S 89 

MT-1 Xmtr 39 

MR. I Receiver 49 

DX-20 Xmtr 24 

DX-35 Xmlf 29 

DX-40 Xmtr 34 

DX-60 Xmt- 59 

DX-lOO Xmtr 85 

DX-IOOB Xmt- 99 

TX- 1 Transmitter 1 E9 

HX-ll Xmtr 29 

HW,|2 75m Xcvr 99 

HW.32 20in Xcvr 89 

VF-I VFO 17 

HG.IO VFO 29 

HW.IO Ten'er 29 

HW-[0 6m Xcvr 169 

VHF'l Seneca 159 

HP-20 AC Supply 25 

MP- 1 DC Supply 2S 

UT-1 AC Supply 19 

HO- 1 3 Hamscarr 49 
HA- 1 4 Mob. Linear 95 

HP- 14 DC Supply 75 

HP-24 AC Supply 50 



HUNTER 




2000A Linear 


$325 


JOHNSOH 




Adventurer 


S 25 


Chaltenger 


59 


Viking 1 


49 


VikinE n 


69 


1 22 VFO 


19 


Ranger 1 


89 


Ranger 11 


169 


Valiant 1 


139 


Valiant 11 


239 


500 Xmtr 


349 


Pacemaker 


149 


Courier Linear 


139 



275W M'boK'SWR 69 
Hobile Xmtr (AS-IS) 25 
Hobiie VFO (ASIS) IS 

KNIGHT 

R-55 Receiver S 39 

R'55A Receiver 44 

H-IDO Reeeivef 59 

R-100A Receiver 69 

T*SO Transmitter 24 

T'60 Transmitief 34 

T-(50 Transmitter 59 

T-I50A Xmtr 69 

V-44 VFO 17 

X-IO Catibrator 5 

LAKESHORE 
Phasemaster MB SI49 
PP-400GG Linear 99 
Srgnal Splitter 29 

LAFAYETTE 
HE-3Q Receiver £ 39 

HE-45 Xcvr 65 

HE-45B Xcvr 75 

HE-6IA VFO 15 

HA-90 VFO 29 

KT-320 Receiver 49 



NATIONAL 

SW.S4 Receiver S 24 

NC-57 Receivef 4"; 

NC-60 Receiver 39 

NC-9e Receiver 69 

NC^IOS Receiver 75 

NC'109 Receiver 79 

NC-125 Receiver 69 

NC-155 Receiver 99 

NC*173 Receiver 69 

NC-183 Receiver 09 

HC'I83D Receiver 149 

NC-188 Receiver 69 

NC-270 Receiver 119 

NC-300 Receiver 149 

NC^303 Receiver 249 

VF0^62 34 
XCU-300 Calibrator S 

HRO-60 Receiver 225 

NTS^I Speaker 9 

NTS-3 Speaker 12 

NCX-3 Xcvr 189 

NCXA Supply 7S 

NCXO Supply 75 

NCX-5 Xcvf 395 

WCL-2000 Linear 425 

PliH 

LA'^m Lir>ear S 69 

LA-40{IB Lirtear 79 

LA-40DC Linear 89 

POLYTRONICS 

PC-6 6m Xcvr £175 

62B 68.2m Xcvr 225 

RME 

DB^23 Presclea S 25 

4300 Receiver 69 

4302 Speaker 9 

4350 Receiver 89 

435DA Receiver 99 

690O Receiver 149 

SB E 

SB*33 Xcvr S17S 

SB-34 Xcvr 275 

SBl-LA Linear 125 

SB^DCP Supply 35 

SB3-DCP Supply 7S 

SINGER 

PR-1 Panadaptor S 99 

SONAR 

20m M<mdfean<ief S 99 
AC- 10 AC SuM>ty 75 
DC- 10 DC Supply 75 

SWAN 

SW^i20 Xcvf SM9 

SW- 1 40 Xcvr 1(9 

SWH75 Xcvr 119 

SW-240 Xcvr 189 

5W*il7AC ffor 2401 6S 
S*-l I7B AC Sup 50 
SW- 1 2 DC Supply 75 
SW-3S0 Xcvr 299 

SW-II7XC AC Sup 75 
TMC 

GPR-90 Receiver S22S 
GPR-90 Speakt^ if 
GS8-1 Slicer 75 



LOUDEHBOOMEft WATERS 

rife n Lifiear (RF) SI 25 Coda>t Keyer 



HELP WANTED ! 

Shipping Clerks 

Ele^^onic TecHnicians 

Counter Salesmen 

Send picture, resume, and salary require- 
meAC. , Would consider helping wjiii mqvin£ 
expenses for out-of-town appiicant. 



64 



73 MAGAZINE 



R 



©SWAN 



©SWAN 



lOOK at your low Monthly Payment 

AFTER JUST »55^ DOWN 




I0"80m Transceiver (14.98) 

400 IO-80m Transceiver less VFO. ,.* (14.98) 
250 Transceiver for 6 Meters ».«•«,.. (I L5S) 

Mark I Linear — less Cubes • (16.97) 

Two 3-400Z Tubes for above. , , * (2.27) 

405 MARS Oscillator - 5 fixed channels (L44) 
406B Miniature Phone Band VFO, .-•.. (2.52) 
410 Full Coverage VFO*. ...**•*,.... (3,25) 
IJTXC H7vAC Supply w/cabinet&spkr (3.25) 

230XC As above, but for 230 volts (3.61) 

II7XB ll7vAC Supply only— less cabinet 

& spkr. (normally used with 400). .... (2.52) 
230XB As above, but for 230 volts .... (2.88) 

14-1 17 l2vDC Supply w/cable .* (4.51) 

14-230 As above, but w/230v Basic sup (4.87) 
II7X Basic AC Supply ONLY*. ...(2.16) 



* ♦ 



(2.52) 

(2I«) 
(2.34) 



« » # * . 



t* * 



230X Basic AC Supply ONLY .. 

I4X I2v DC Module & CabJe 

I4XP As above, but Positive Ground 
Cabinet, Speaker & AC Line Cord . . 
I I7v or 23 Ov Line Cord (specify) 
8' Power Supply Cable w/Jones Plug 

VX-I Plug-in VOX 

SSB-2 Selectable Sideband Kit for 350*. 

22 Dual VFO Adaptor for 350 & 400 

lOOkc Calibrator Kit for 350 
SOOkc CaUbrator Kit for 250 
lOm Full Coverage Kit for early 350*5,* 

55 Swantenna — Remote Control (3.25) 

45 Swantenna — Manual ........ . « * . * * (2. 16) 

Deluxe Mobi le Mounting Kit, . , — . . * * * 
RC-2 Remote Control Kit., 



• • 



• f • 



* . 



* * 



r 




$420.00 

420.00 

32S.00 

47S.00 

68.00 

45.00 

75.00 

95.00 

95.00 

105.00 

75.00 

95.00 

130.00 

140.00 

65.00 

75.00 

65.00 

70.00 

30.00 

5.00 

3.00 

35.00 

18.00 

25.00 

19.50 

19.50 

15.00 

95.00 

65.00 

19.50 

25.00 



Ttie payments shown above are for a 36-month time-payment 
plan with S5.00 down. The minimum total order that may be 
financed for 12 months is S60.00; for 24 months - S120.00; 
for 36 months - S130.00. NOW! Our time-payinent plan offers 
a lOS-day pay-off option! 




AMATEUR 




1 



I ook no further ! 

The Best Deals (Trade or No Trade) on 

New Swan Equipment are being made at 

AMATEUR ELECTRONIC SUPPLY 




GET OUR 
DEAL TODAY! 

Use Hand/ 

Coupon 
Below 




Terry Sterman, W9DIA 
Proprietor 



Ray Grenter K9KHW 
M£f*Mail Order Sales 



I To: AMATEUR ELECTRONIC SUPPLY 

I 4828 West Fond du Lac Avenue 

I Milwaukee, Wisconsin 53216 7 

I 1 am interested in the following new equipment: 
I 

I 



FIP#^TDA|y|#^ |lhave the following to trade: 



{what*s your deal?) 



SUPPLY 

4828 West Fond du Lac Avenue 

Milwaukee, Wisconsin 53216 

Phone (414)442-4200 

MILWAUKEE STORE HOURSi Mon & Fri-9 am to 9 pm; 

Tues, Wed. Thurs-9 am to 5^30 pm; Sat -9 am to 3 pm 



I enclose $. 



fMPORTANTI — Be sure to send all Mail Orders and 
Inquiries to our Milwaukee store, whose address is 
shown above- VISIT — Please do not write the fol- 
lowing Branch stores - they are set up to handle 
walk-in trade only- 



Q COD □ lyear [^2 years □ 3 years 



CHICAGO, ILLINOIS 

64S0 Milwaukee Avenue 
Phone (312) 763-1030 



ORLANDO. FLORIDA 

19 Azalea Pk.Shpg.Ctr« 
Phone (305) 277-823 I 



CHICAGO Sr ORLANDO STORE HOURS: Mon, Wed, Thurs - 
12 to 9 pm; Tyes & FrI- 12 to 5*30 pm; Sat- 10 am to 4 pm 



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I will pay balance (if any) 



Name 



Address 
City 



State 



Zip 



n Send Reconditioned Equipment Bulletin 



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OCTOBER 1966 



65 



WTW Country List 



AC 1, 2, 5, 6, 7, 8, fl, — Bhutan 
AC3— Slkkim 
AC4— TlbcU 

AP— EftsL Pakistan 
AP — West Pakistan 
BY, C3 — Formosa ( Taiwan) 

CE— €hile 

•rE9 — See KC4 

CE0A— Enster Isliinrf 
CE0X^S«ll Feiii 
€E0Z — Juui Fernaudez 
CM, CO— Cuba 
€N' — Horroco 
Ci*— BollTii 

CB3, 5 — I'ortuguefle Gulncft 
CE4- — Cipe Vfinfe MiTtdi 
CB5 — Prtncipe, Sao Ttiorne 

CR 7 — ^MiMum b I n n e 
OtS — PorlujctiesB Timor 

CTl — l^artueal 

C^— Azores 

CT3 — MftOeria 

€K— Uruguay 

DJ. DX^-^-Oertnan Fetl. Een, West^-BFU 

DL. DJ— West Berlin 

DM — Genuii Dem^craile Be|i, {Eft3t)-1FU 
DO — PMlHpI&cg 
EA — Swia 

EAG — Bal^e Is, 

EAH^ — Canairlx 

ISA0— Ifnl 

EA9— Illo de Ort> 

EAf^- — Hpajnsfi Morroco 

iJA0 — Kio Mmidj & Femaiidc) Poo Is. 

EA0 — Spftnish Guineii 

EI — Reri.of Irekud 

EL— Liberia 

W — Iran 

EA3, Bm, 9r3— Ethiopia 

F- — Frimee 

FB8— Amsteriiam k St. Paul Is* 

FBS — erozet Is. 

raS — KenEuelen Is, 

FBS— Frniff) AnIartI(Ml-R^ 

FC— Cofiiea 

FttT'^-Ouiid&ltHipe 

Filg— Comarwsia. 

FKS-^New Caledonia 

FI^ — Fri*nch ^offiaUlaiid 

FM7 — Mfirtinique 

Vm — Clipjierton Is, 

F08^— Ij)yttlty & tlit'sterfitld Is.-REF 

F08— Toubuiiai (Austrdl Ii.)^REP 

FOS — ^^Tuitmotoii fnambli^r IsJ^REP 

r 08^=-Marque^a Is,-RE7 

FO,^— Auatniil Is. (except Toiilwmail-REF 

FOH—Soclety Is. (TalilUH Ref 

K?~l'' Pierre 4 Miquelon 
FRf — ^Betmioii Is. 

F R7 /G — Glorieases Is* 
FB7/J' — Jumn de Nova k Europe Is 
FR7/T~TfBmUei Is. 
F^7-^^it3t Martin la. 
rVH, y.ll— New HerbidM Is. 
F1V8— AVallis & Fqiiiim Is, 
FY7— Frendi Guimiu, k Inlni 
G, GB — Eni?land 

QC— Gucnm^y & Dcpeiideiiei^ 
QC— ^rere&r In, 

CD— Tal^ of Man 

ni^ — ^Nnrtltt'm Ir^IiiTiii 

CM — Scotland 

CW^- Wales 

HA — linngiify 

HB — SwiUerland 

HE, HB0 — Lieditenfltelo 

HC — E(Iijf"a.dor 

HrH— <jala])agos 

Ht'gE. KXe— Ebon Atoll 

HH— Hif ti 

HI^ — Dominican Bep. 

HK — Colomhla 

HK0— Bajo NueTo 
HK0— Mulpeio le. 

?,^^*f*"..'^"*^^ ^ Frovldenda Is. 

HM— Korean Peoples ttep. (North) 
HP^ — Pajmma 
HE^Mofnliiras 
HS— TiLulond 
HV— Vatican 
*HX— See 7Z 
II- 



ISl — SizYlitila 

ITl— SJcfly-DAKC 
II — Tricstt-DABC 
J A, KA — Japan 



JT^Mrmsolia 

JT — Jordan 

K, W. \VA, WB, etc.— USA 

•KA— See J A 
KUi] — Bilker, Howland k American 

•KC4U— AnUrctka (see CEO) 

KC4 — i^avitssit Is. 

KCi^^EuHteni Can>liri(^ 

KV%S — \Vest*m Cart»iiti«m 

KCfi— Palau-NZAUT 
•Kill— See 0X 

KG4— Utuuitsnado Bay 

Kfiti— Guam 

Kti*; — Marcus Is. 

KGti- -MlLTiiUU l5* 

K«;til — Honio k Vokuno Is* 
KHO-— Hawaii Is. 
Kli^;; Kurt* Is. 
KJ+i idlihson Is. 
K[.7- AJnskii 

KP4 — Puerto Itiea 

Ivltii— Kynku Is. 

KS4— Swan Is. 

KS-IH— ^rrana Bank k Ratieaifor Cai 

Kftft- — American Samoa 

KV4— Virgin Is. 

KUtS— Wake Is, 

KXtJ^Marshan I«, 

KZ5 — Canal Zone 

LA — ^Norwar 

tuiyP— Jan %[a3^en 

LA /P— Bear Ls.-DARC 

LA/P-^falbard 

LH4 — "Bmiret Is, 

LU — Argentina 

LU SJ— (see KC4) 

LX — -]jiiX(."]]]hom'g 

LZ^-BiilijiLrla 

Ml, \^hh — San Marino 

jM P 4 B— Bahrein Is, 

HP4M» VSft— SulUnitc of Muscat k 

Oman 
MPIQ — Qatar 
JfPlT— Tfucial Oman 
OA — Pera 
0D5 — l^banoe 
OE — Auhtria 
QH— Finland 
OH 0^ Aland 
OK — V7^ rhoKloTakJ a 
UN"— Bclh'iuin 
or{4_(8t,e KC4) 
OX, XP — (ireenlaod 
OY — Faroes 
055 — Il€n marie 
PA0, Pll— NetlierlajidB 
PI — ^Dutch W^ Indiia 
PJ2M— SInt Maarten 
PX — Andorra 
PY— Brazil 

Py0— Femantto de Koronlia 
PY0 — St. Pet*r-&-Paul Rocts 
PY0 — ^Trindade k MSfUm Vaz la, 
P2~&jBlnaBi 
SL> Sil — Svfeden 
SP— PolaJid 
ST—Sudan 
Stf— Egypt 
iSV — (3ni«?oi? 
%V- — Dodtx-^anese Is, 
SV— <>tie 
TA-^Turkey 

TA — Etiropoan Turkey-DARC 
TF^Iccland 
TG — Giufcermala 
TI— Com Rica 
TI 9— Cocoa Is. 
TI9C — C^moran RecT 
TJ — Camerotin 
Tl^rpiitral Mrit'an ttcp. 
TX— 4'nngo Rep. 
TB^^iaimn Eep. 
TT— Chad Rep. 
TtJ — Ivory Const 
TY — Iklinincy Rep. 
TZ— MaU Rep. 
IIA, TJV, CVV 1 thru 6— Bufopean Rusaia- 

RFir 

UA— Ru^an Antartica-BFO 
UAl — Finns Jcj^flan4 
tTA2 — ^K allnln gradsJc 
UA. liW, S, — Asiatic Risstft 
UA0 — Dickson Is.-EFl' 
UA0— Magadan Is.-RFU 
UA0— Tniniar-EFU 
UA0 — ^Tnvm A3SH RPtJ 
IJA0 — Cbokot^k-RFr 
T!A0 — Yakut ASSlMtFU 
UA0— SaklUln Ohl.-RFU 
UB5, tJT5— Ukraiii 



11C2— Wliite Russia 

UDfln-^Aiefbajjan 

IjFB — Georgia 

r< ill— Armenia 

TTH^^— Tiirkoram 

UJ,S— Uzhok 

VM — Tsibzhik 

Vhl — 'Kai^akh 

ITAIS — Kirghiz 

I'Nl'-Karelfj-Flurtiaii Rep. -D ARC 

rn5 — ^Molilnda 

T:P2 — Lilhuania 

Mm — Latna 
1112— Estonia 

VE, VO— Canada 
*\0— S*^e VE 

VK — Ansirnlia 

VK— Lord Howe Is, 

VIC4— WlilJs Ik. 

VlCB^rhiistmas Is. 

VK9— Cocos Is, 

VKy— Nauru Ih, 

VKft— Norfurik I3. 

VKll— Pajiiia TwrrJtori* 

VKH — Territory of New Guinea 

VK0— Heard Is, 

VK0 — ^Mai^iuaile Is, 
*VK0^.See KC4 

\T1— -British Hotidnraa 

\T2— Antigua, Barbuda 

VP2— Aj:^ma 

VP^— British Virgin Ii. 

VP2 — Dominica 6. 

Vr*2— 43renada Is. 

VP2— Moiistserrat 

VP2— St. Kitts and Netis 

VP2— Ht. Lueia 

yP2— St. Vincent Sl Dcpendfinclea 

VP3— British fkiirina 
*VP4 — Si*e 9T4 

VP5— Turks k Caicos 

VPH — Barijukis 

VPT-^Bahaiaas 
•\T8--Be« KC4 

VPg— FailOand Is, 

VPS — So. GeoTHa 

VPS^-^. Orkneys 

\p5i^&i, Sindwkh Is. 

VPS^go. Shetlaada 

VP — ^Bfrmuda 

VQI — ^Znn^ibar 

vSS"^5F^^^* & St. Br«ndon 
VQg — chagos 

VQg — Mauritius 
VQ8— Roiirlgiiea la. 
VQD— Aldabra Is. 
V(i9 — Seychelles 
VQ!3 — ^Dearoches 
YQt^— Finniabar Is, 
^1— BriOfib Phoenix It 

VRI^ilbm. Elis, k Ocean Is. 

Mt2 — Fiji 

y^'J— ^'*n^iing k Chfi^maa Is. 
VK4 — Solomon Is, 
\m — Teoga 1st 
VB6— PitcAirn la. 
VSS^Brunei 
VS6— Hang Kmg 
vm — A(ien k Swotra 
VS0H^— ICiiria Mauria Is. 
V89K— Kamaraji Ib. 
VS9M— Maldive Is. 
VIT2— AiidaittaE k Nicolmr Is. 
VU2— India 
VtF2-=-Laecadive Is, 
*W— See K 
XK. XF^ M*^ico 
XE, XF^lkrilla Gigado 
XT— Voltaic Rep, 
XU— Ctntbodli 
XV— South Viet Nun-BFU 
XVV*8— Laos 

xm — BnrmA 

TA— Afuhanistan 

YI— Iraq 

TK — Syria 

\H — Nicaragua 

VO — Rumania 

YS — Saltador 

Y'U---YilgQslai'ia 

yv — Ve»esuek 

VT0— AT«S Is. 

M — ABania 

ZB2— Gibralta- 

ZD3 — Gambia 

ZD 5 — Swaziland 

ZDZ^t. Helena 

ZOS-^-Ascenslon 

2D9^ — Gougb & Tristan de CtJnha 



66 



73 MAGAZINE 



S&E — Rhodesia 
S£Pl^-Caym?in Ja, 
ZKi — Cook Is. 
ZKl — Maiiihikf Ii 

ZL — Ctiathvii Is. 

SSL — ^Kermidic Is. 
55t— New Zealand 
•ZL5— Set KC4 
ZM6 — Wfr^^ern Bttmoa 
KM7— Tokalaus Is. 
*h?' — Para pi ay 

ZSl. 2. 4, 5. B-^Smith Africa 
ZS2— Itjiirlon k I'rinw Edward Is. 
Zi?3 — .South Wftst Afriai 
ZS7 — SwiiziJand 
ZS8— Ba^utoland 
2S9 — Bechuanaland 
1M4 — -Maria Teres4 
1S9 — K|)riitlfiy Is, 
3A — Monico 



3V8^ — TuDLsia 

3WS— North Viet Nani-RFU 
4.^7 — Ceylon 

4U — \JIM, Genefa, Switzerland 
4W — Yeman 
4X — ^Israel 

4X1 — IsTftd/JordAn Dcmilltanaed £one 
5A — Libya 
5B4 Z€4 — Cyprus 
5H;];— Tangsiiiyika 
5N2— NJgtria 
5 SS-— Malagasy 
5T — Mauranfania Bap. 
5U7 — Niger Bup. 
5V— Tofo Eep. 
*5W1— See ZMG 
5X5 — ^Ueanda 
5Z4 — Kenys 
60 — Somali Rep, 
6WS — Senegal 
GY5 — Jamaic4t 
7G1 — Bep. of Guinea 



All countries ire ffom ARBL IM eictpt tliose marked vltli ou« of 

Uk* roilovrlTiif: 

DABC — Deutscher Araat«tir Radio Clnb (West Germany) 

NZABT — Kew Zetjand AssocitUon of Radio TnuiimJttera 



707 — Malawi Rtp. 

7 X— Algeria 

7Z(HZ)^iudi Arabia 

SF— XndoneBla 

ggi^Saudi Arabia/Irtq Neutral Zone 

gZS, &K3— Kuwilt/Saudi ArabU Neulrml 

Zone 
■9A1 — See Ml 
*9B, 9F — See ET 

9G1— Ghana 

8H1— Malta 

%\% — ZamlUa 

9K2 — Ktra'riit 
•BK3— Set* kZ5 

%\s\ — Sierra Leone 

9SI2 — ^West M&lifsia 

9M6« S — East Miiafslft 

^M 4— Singapore 

9N1 — Nepal 

gQ5 — Rup, of the Congo 

9U5 — Burinuli 
9X5 — ^Rwauda 
9Y4 (\T4) — Trinidad and Tobago 

HI'jF— Rlttau des Etnetteurs Fraacali {France) 

RFC — RadlcHiriort FpdLTatioTi irfT the U&SR 

Ttie asterisks indicaie addlLiDDml pniflxcs for a country. 



The WTW and You, 




Gus Browning W4BPD 
c/o 73 Magazine 
Peterborough, N.H. 



DX'er 



The Fall DX Season is upon us again. This 
is the time of vear when the DX will be com- 
ing thru with those strong signals. With the 
sun spots getting a little bit more plentiful 
every month, DX*ing will be FB for a good 
many years now. After that tiie spots will taper 
off and we all will be getting older and older. 
By the time the next peak comes around some 
of us won't be here to enjoy the FB DX'ing 
that can and will probably take place again. 
Or by that time tlie frequency allocation con- 
ference will have taken place, and maybe our 
bands will all be stolen from us by the com- 
mercials or other folks that are eyeing them 
right now. So I say if you are interested in 
working DX, now is the time to get started. 
Get in on the fun while the bands are jumping 
with plenty of DX* 

Of course if you are stuck with the ARRL*s 
DXCC you have had it! You have just "worked 
yourself out of business*' if you have been 
widi the DXCC all these years. There just 
isn't anything on the bands tliat you need, so 
you can put a cover over your rig and go take 
a look aL TV or go fisliing. But there is a solu- 
tion to your problems in the WTW. To qualify 
\s\ the WTVV competition all QSO*s have to 
have taken place since 0001 GMT May 1, 
1966. Now this puts lots of countries in the 
"rare" side of your ledger, I would estimate 
that well over 100 countries have not been on 
the air since May first. Is that not better than 
having maybe Just one or two rare ones left 
like the DXCC? At least you have some 
DX'ing to do and that*s better than 75 meter 
ragchewing or traffic handling. There is plenty 



for you to do if you like to work DX for the 
all new^ WTW DX award. Remember there 
are certificates for 100, 200, 300 and 350 
countries, as well as a WTW for each band, 
and each mode. There is no mixing of the two 
or tlie bands, either- Everyone starts at the 
same point. The newcomers to DX'ing have 
the same chance as the old time DX*er, 

Our counlrv Hst is a reasonable list. It's 
made up of all the countries on ARRL*s DXCC 
list plus a few that tlie Radiosport Federation 
of the USSR recogni2:es and a few others from 
the REF of France and the NZART, Others 
will be added when we hear from the other 
nationally recognized amateur societies of 
overseas nations* We are not including any 
countries just because we think they should 
be in the WTW Ust. All countries were sug- 
gested by others, not us. We don't want any- 
one to "button hole" us at some convention or 
gathering and ask us why such and such a 
place Is a cotintry^ and such and such is not. 

Of course if you are a tired, lazy, waslu^d- 
out DX er, the WTW is not for you. It's for 
the wide-awake feUow who wants to do some- 
thing, one who is tired of just sitting in his 
shack twiddling his thumbs with nothing to do 
but gaze at his rig and yawn and go out to 
that TV set and gaze at it. You just keep on 
with tlie DXCC. It's your meat. The top fel- 
lows in the DXCC have nothing much to look 
forward to- Of course, they may need ZA or 
YI or mavbe one or two others and ^vith all the 
weekly DX bulletins you know if any of these 
will be on well in advance so there is abso- 
lutely nothing for you to do. The days of 



I 



OCTOBER 1966 



67 



-1 



^ 



call 



name 



mode and band 



address 



number of countries 



List of stations worked {with date of QSO) in alphabetical 
order. This list can extend to the back of the card* 



On the reverse ; Name, call and signature of person submitting 
or verifying cards and date* 



Please use this format (shown full size) for submitting applications 
for WTW award. Send to Gus, 73 Magazine^ Peterborough, NH 03458. 



**sneakmg home** from work like back in the 
50's has gone as far as the DXCC is concerned* 
But this can be done right now with the 
WTW. The WTW will bring back the "good 
old days" for all of you, even the newcomers. 
There is plenty of real good stuff on for the 
serious minded WT^V DX'er—biit not for the 
top boys in the DXCC. The DXCC certainly 
was a good deal for the boys a few years ago, 
but, fellows^ those days are gone. This WTW 
is a modern-day DX'er's wish come true. Get 
in there fellows and join in on the fun, It*s 
wailing there just for you. 

We are gradually getting "ver^cation 
clubs" lined up for the awards. We don't want 
any one to have to mail his QSL cards away 
from Ins continent, and in the ease of USA 
hams we want to have a "verification club" in 
each call area* We still need a few to fill in 
here and there and are looking for volunteers 
yet in a few places. Any of you club members 
in the areas not yet covered, how about taking 
this up at your next club meeting and submit 
your club for consideration to mCj c/o 73 Mag- 
azine. No indi\iduals please— only recognized 
clubs. Here is a full break down on how we 
now stand: 

Asia—We yet need one here 

Africa— Also still needed 

Oceania— Also needed 

Europe^Via RSGB 

South Ainerica— Venezuelano Radio Club» 
Caracas 

Canada— Edmonton Radio Club 

W/Kl"Still needed. 



W/K2-Still needed. 

W/K3-Still needed 

W/K4— Virginia DX Century Club 
(W4NJF) 

W/K5-Still needed 

W/K6-0range County DX Club (W6KTE) 

W/K7-Westem \^^ashington Radio Club 
(W7PHO) 

W/K8-Still needed. 

W/K9--StiU needed. 

W/K0-Still needed. 

We ask all verification clubs and hams to 
use a unifonn method of submitting to me the 
information on the DX ers who qualify. Please 
use the form shown- This will make my task 
a lot easier and we aU will be using the same 
system of keeping records. 1 strongly suggest 
you keep a similar list on filing cards for future 
reference if needed. Note to verif>dng clubs: 
Be sure to return the cards to the sender^ 
fellows. We don't want anyone accusing us of 
slow service, lost cards, stolen cards, and other 
type things that I have heard about some other 
awards that require QSL cards. Let*s all really 
give the DX'ers fast service and no monkey 
business. 

Will close tliis little article with a reminder: 
I shortly will start putting out a weekly DX 
magazine. The DX'ers Magazine. It'll help 
yoii keep right up to the minute on current 
active DX, Most of the good DX is past history 
by the time it's in a monthly magazine, you 
know. This is something entirely diflFerent— 
something that no monthly magazine can do. 
Let me hear from you. , . . Gus 



68 



73 MAGAZINE 



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OCTOBER 1966 



m 



J, H, Nelson 
157 Fernwood Terrace 
Stewart Manor 
Garden City, N.Y, 

The Future of the 10 meter Band 

The text of a talk given May 14 hy 73's propagation 
columnist to tfie North Jersey DX Association. 

About the 10th of April, 1966 I received 
a telephone call from Mr* Bob Stankus 
W2VCZ, He asked me in a very casual man- 
ner^ as if there were nothing to it, if I would 
predict for the North Jersey DX Association 
the future of the 10 meter band. I did some 
quick tliinking and realized immediately that 
in order to predict the future of the 10 meter 
band I also had to predict the future of the 
present maspot cycle. I do not like to predict 
the sunspot cycle because after 20 years re- 
search on sunspots I have come to realize how 
whimsically the sun can behave- I also know 
from history that some pretty important as- 
tronomers and researchers had gotten into 
trouble working on tins subject in the past- 
many of them knowing far more about the 
subject than I do. However, I considered the 
subject as a challenge and decided to see 
what I could come up with, I had quite a bit 
of data available on past sunspot cycles to 
use as research material 

First, I went into the history of frequencies 
near the 10 meter band in the archives of the 
RCA Frequency Bureau and found that RCA 
Communications started to experiment with 
31 MHz which is of course slightly less than 
10 meters, earl)^ in 1930. The experiments 
were conducted with Buenos Aires. RCAC 
using W2XS on 31420 KHz and Buenos Aires 
using LQB2 on approximately the same fre- 
quency. Unfortimately this was near the be- 
ginning of the 1930 sunspot low and the 
project liad to be suspended until we got into 



the area of high sunspot numbers between 
1936 and 1938* These frequencies were then 
run simultaneously with norma! communica- 
tions frequencies, which were on about 21 
MHz and received on a dual tape recorder 
so that the messages tliat Buenos Aires was 
sending would appear^ one above the other, on 
the same piece of wide tape. As an experiment 
the operators were ordered to copy the higher 
frequency whenever it was useful even though 
tlie lower frequency was still satisfactory, I 
further found in the archives of the Fre- 
quency Bureau that tlie amateurs were alio- 
eated the 28 to 30 MHz band in 1927 for ex- 
perimental purposes according to the records 
of the Madrid Conference in 1932. So the 
amateur preceded the commercial stations in 
the investigation of this band. They proved 
its usefulness. 

Since the eaily 1950*5 the receiving tech- 
Tucians at the RCA Communications receiving 
station at Riverhead Long Island have kept 
meticulous "two hour" records of the lowest 
and highest frequency readable from the 
European area. At tlie same time, they also 
record the quality of the signals in this band, 
I went thi'ough these records for the years 
1955 to 1960 inclusive and determined the 
number of hours per day throughout the whole 
of eacli year that frequencies between 26 and 
30 MHz were recorded as good* The data 
sliown l)v these records is presented in cliart 
A, 

An examination of this chart shows quite 





1< 


^55 


1956 


1957 


195S 


T959 


19 


60 




A 


B 


A B 


A E 


A B 


A B 


A 


B 


Jan 





20 


4 70 


134 152 


234 202 


208 217 


76 


139 


Feb 





21 


123 


94 117 


148 165 


172 143 


S8 


103 


Mar 





5 


4 116 


72 167 


tOd 191 


1 86 1 86 


80 


103 


Apr 





11 


1 05 


V4 175 


24 1 96 


42 1 63 


4 


120 


May 





29 


NR r36 


165 


8 175 


172 


16 


119 


June 





33 


n7 


205 


14 171 


169 


4 


109 


July 





26 


128 


194 


191 


149 





119 


Aug 





40 


171 


4 163 


8 200 


19S 





131 


Sept 





4T 


40 182 


88 244 


84 201 


12 145 


10 


125 


Oct 





59 


NR 161 


T22 263 


220 181 


48 111 


8 


81 


Nov 





90 


146 203 


212 207 


230 152 


44 124 


38 


87 


Dec 





77 


172 185 


1 94 233 


184 187 


66 125 


34 


83 


TOTAL 





452 


366 T697 


934 2285 


1260 2212 


778 1902 


358 


1319 



A— The number of hours between 8 AM 
hAHZi ond 30 MHz were logged as good 
station of RCA Communlcafions, Inc* 
B — The Zuerich monthly sunspot number. 



and 2 PM EST (1300 GMT and 1900 GMT) that frequencies between 26 
from Centre I Europe of the Riverhead, Long Island^ New York receiving 



Chart A. Comparison of sunspot numbers with stations received on 10 nneters. Compiled by J. H. Nelson 
of RCA Communications, Inc, 



70 



73 MAGAZINi 



drafnatically the good con elation there is be- 
tween tlie houiK of usefuhiess of these higher 
frequencies and the yearly sunspot number, 
lo 1955, with a yearly sunspot number of 
only 452, Riverhead logged no hours of use- 
fuhiass on frequencies above 26 MHz. I would 
like to point out however that this does not 
mean that these frequencies did not break 
through occasionally since the technician does 
not keep a constant watch for them. He in- 
spects the band every two hours on the liour. 
As we go into 1956, the yearly sunspot num- 
ber increased to 1697 and the hours of use- 
fulness rose to 366. In 1957 yearly sunspot 
numbers rose to 2285 and the hours of use- 
fuhiess increased to 934. In 1958 the sunspot 
number stayed above 2000 being 2212 and 
the hours of usefulness increased to 1260. In 

1959 tlie sunspot numbers began to drop 
showing a yearly number of 1902 and the 
useful hours of these frequencies dropped to 
778. In 1960 the sunspot number dropped to 
1319 and the hours of usefulness on these 
frequencies dbtopped to 358. In 1961 we find 
that these frequencies did not show up in the 
records at all although as I have said before 
there were prol>ably occasional periods where 
they would have been heard if we maintained 
constant coverage. 

I would also like to point out that these 
frequencies have very httle or no usefulness 
during the summer months. They l)egin to 
show up in September and fade out in April. 
The data shows this very clearly. 

The sunspot numbers that are shown here 
are the montlily averages. When these aver- 
ages are smoothed into 12 month smoothed 
averages we find that the smoothed curve be- 
gan with 14 in Januar) 1955 and increased to 
81 by the end of the year. In 1956 it began 
with 89 and ended with 164. In 1957 it began 
with 170 and ended with 200. In 1958 it be- 
gan with 199 and ended with 180, In 1959 
it began witli 179 and ended with 132. In 

1960 it began with 129 and ended with 84. 
It appears that a smooth sunspot number 

in the neighbor! lood of 80 to 100 is necessary 
before tliese frequencies come to life. Data 
on this phase of the subject appears in Chart 
B. 

Data on this chart pertains to sunspot num- 
bers and sunspot cycles from 1755 up to 1964. 
It was analyzed in the fono\ving method in an 
eflFort to produce a teclmiqiie whereby it 
miglit be possible to anticipate the trend of 
cycle number 20 which started in 1964. 

I analyzed the sunspot records by several 
different metliods before I came up with what 
is shown in tliis chart. Examination of past 
sunspot cycles indicated that low maximums 





Low 






High 


Cycle 


Year 


A 


B 


Year 


1 


1755 


19 


87 


1761 


2 


1766 


7 


116 


1769 


3 


1775 


12 


158 


J 778 


4 


1784 


9 


141 


1788 


5 


1798 


37 


49 


1 803 


6 


1810 


64 


48 


1816 


7 


1823 


44 


71 


1829 


8 


1834 


16 


146 


1837 


9 


1843 


9 


132 


1348 


10 


1856 
Low 


23 


98 


1860 
High 


Cycle 


Year 


A 


B 


Yeor 


1 1 


1867 


14 


140 


1870 


12 


1878 


33 


75 


1883 


13 


1889 


37 


86 


1893 


14 


1901 


33 


64 


1906 


15 


1913 


45 


105 


191 7 (Short 
Peak] 


16 


1923 


18 


78 


1928 


77 


1933 


23 


120 


1937 


18 


1944 


3 


150 


1947 


19 


1954 


17 


200 


1957 


20 


1 964 


10 


(135) 


(1968) 


Totol 




46B 


2064 




Average 




24 


108 





A — The number of months with a sunspot number of 
10 or less during eoch low period. 

B — The maximum smoothed sunspot number of the fol- 
towing high period. 





C 


D 


E 


F 


G 


H 




19 


87 






37 


49 




7 


116 


7 


116 


64 


48 




12 


158 


12 


158 


44 


71 




9 


141 


9 


141 


23 


98 




16 


146 






33 


75 




9 


132 


9 


132 


37 


86 




U 


140 






33 


64 




18 


78 






45 


105 




8 


150 


8 


150 


23 


120 




17 


200 










Total 


129 


1348 


45 


697 


339 


716 


Average 


12.9 


134.8 


9 


139.4 


37.5 


79.4 



C — The low periods with 20 or less in column A, 

D — ^The sunspot number in column B. 

E — The low periods with 12 or less In column A. 

F — The sunspot number In column B. 

G — The low periods with more than 20 in column A. 

H — ^The sunspot number in column B. 

Chort B- Complied by J* H. Nelson of RCA Com- 
munications, (nc, 

were preceded by prolonged periods of low 
minimums and high stinspot maxiniums were 
preceded by short minimums, 

Afler several different attempts I found 
that if I counted the number of months with 
a suaspot number of 10 or less during each 
minimum period I got the best correlation in- 
dicative of what the following higli was going 
to be like* I won't go through this chart item 
by item but I would like to point out to you 
that in Column A we have listed the number 
of months that 10, or less than 10, sunspots 
were recorded, and in Column B is shown the 
maximum smooth sunspot number for the 
high period that followed a few years later. 
These data sliow quite clearly tliat the higher 
maxima were preceded by short low periods, 
and the low maxima were preceded by long 
low periods. This will become apparent to 
you when you stud)' the chart closely. 

On the lower section of the chart under 
Colunui C I have listed all the low periods 
that had less than 20 m.anths duration and in 



I 
I 



OCTOBER 1966 



71 




] 



-fiC 



30 



20 



ft 



10 

e 

7 
5 



S 8 





[ 1 


1 1 


1 i 


1 


1 - 


; 


1 - 


1 — 








OHCUtT - EASTEFm USA TO LONDON 

p 1 i 










MONTH - NOV. I960 


/ 




^ 


\ 










N 


UMBE 


R OF 


105 


WVI 


y 








\ 


\ 














it 










\ 


\ 


**^ 


\ 


^^ 




/ 












> 








^^^ 


f 








































































































































































































































































8 8 8 



m 



■c 



id 



8 S 



IM 






GMT 



Fig, K MUF versus time of doy, November 1960. 

Column D I have listed the sunspot maximuin 
associated witli each of these periods. You will 
note that out of the 10 periods listed that had 
relatively short minima there were 8 with 
fairly high sunspot nionbers during llie fol- 
io wing maxima. 

In Column E I have been even more selec- 
tive and picked out the periods that showed 
on]> 12 or less in Column A and here you see 
at a glance that tliese shortest periods of 
minima were followed by quite high maxima. 
The average lengths in months of these shorter 
periods was 9 months and the average sun- 
spot maxima comes out to be 139, 

If you would refer to the top of the chart 
and pick out cycle 20 you will see that Col- 
imm A carriers the figure of 10 indicating that 
the 1964 low had 10 montlis with a sunspot 
number of 10 or less, A figure of 10 in Col- 
umn A predicts a following maximum in the 
neigliljorhood of 135. This analytical tech- 
nique tlierefore predicts that the sunspot num- 
ber in 1968 or 1969 will reach a smooth 
sunspot number of at least 135 %vhich should 
open the 10 meter band to Europe quite well 
from September to April. 

Column G and H indicates that prolonged 
minim urns were followed by low maxim uni§- 
You can see from the data that when the 
average length of a miinmum was 37,5 
months, the average of the following sunspot 
maximum was only 79.4. Of tfve 9 items listed 
in Column G, seven of these items correctly 
predicted that a low maximmn would follow- 
Two items were in error but not seriously. 

To recapitulate, if we were to bet on a sun- 
spot number to be high using the figures in 
Column C we would have been right 8 times 
out of 10. It we bet that a sunspot maximum 



was going to be low we would have beeri 
right 7 times out of 9 according to the figures 
in Column G, This particular approach indi- 
cates a stiong probability that tlie figure as- 
sociated witli cycle 20 stands an 80% chance 
of being correct. But let me point out once 
again to you that 1 am not an expert in sta- 
tistical analysis and this coupled with the fact 
tliat simspot cycles are very diificult to pre- 
dict causes me to warn ) ou that T might be in 
error* 

I have prepared two graphs that can be 
used as a further guide in anticipating the 
future. This first graph (Fig. 1) shows the 
type of MUF curve associated with a 
smoothed sunspot number of 105- It is for a 
circuit betw^een Eastern U,S. and England. It 
can be seen from this graph that the most 
likely periods of the day for 10 meters (or 
28 MHz) to be in operation are between 12 
and 19 CMT in November. The next graph 
(Fig. 2) sliows the November MUF for the 
same radio circuit based on a smoothed sun- 
spot numl:3er of only 65. You will notice that 
ihis lower smoothed number predicted a MUF 
barely above 30 MHz. This indicates that 
somewhere between a smoothed number of 
65 and 105 the 10 meter band \% going to 
become operational This figure is probably 
close to a smoothed sunspot number of SO 
which should appear during the 1966-67 
winter. 

The statistics preset Ued and analyzed in 
this report predict that 10 meters should 
come to life, at least spasmodically, between 
U.SA, and Europe during the coming winter 
(1966-67) and should be well established by 
the following winter. . . . Nelson 



iiLj 

UJ 




GMT 



Fig. 2. MUF versus time of day, November 196K 



72 



n MAGAZINE 



SWAN PRODUCTS AREN'T PERFECT! 

Over a year has elapsed since I first enthused uver the Swan 350 and 400. 
So ecstatic was I in ex toll in g their virtues that I began composing idioms 
which expressed their value in comparison with brand X or Y. I had even 
come up with a quotient of value (frequency coverage times power divided 
into dollars). Oh — -I felt I had something and so I called Herb Johnson, 
founder and owner of Swan, to see how he'd i-eact to my "baby/* WTiile 
reading it to him I emphasized certain phrases and words — expecting him 
to say — ^"that's right or fine" — \^Tien I was all through there was a deathly 
silence. No comment — no voice at all — "Are you still there Herb, I asked"? 
And after a further pause Herb's low voice saying, "I don't like what you've 
written — Vd rather you didn't print it. Our gear isn't perfect — we have had 
our troubles and we're a long way from being satisfied, etc., etc/^ 

I felt disappointed — yes — but when I stopped to ponder Herb's remarks I 
realized only too well that he w^as right and therein lies my message about 
Swan — the eontimions improifementB which you never see listed in any ad 
nor in any instruction manual and which make a fine set still better. 

Example: When the 350 was first produced it drifted a little too much — 
Swan found that they could reduce the drift 3 to 1 by physically isolating 
the transistorized oscillator in a little box under the chassis. 

Example: It was found by using ceramic forms in the VFO— a further 
6 to 1 improvement resulted. 

Example: By winding their tank on a ceramic form they reduced the 

possibility of tuneup warmth melting or changing the shape of the original 
air wound coil 

Example: By changing the tuneup procedures with a simple circuit change 
you no longer have to worry about exceeding the dissipation ratings of the 
final — even for as long as several minutes. 

Example : The 10 meter band is complete now ; earlier models covered only 
part of the range, 

I could go on and on — because this list isn't complete — The Swan 350 isn't 
perfect, but it's constantly being improved and for those who own an early 
version, the factory will up date yours at a very modest charge. Show me a 
better set and 111 eat that proverbial hat. 

And for you fellows who want to know where the word "Swan" comes 
from — rn tell you. Herb Johnson's father's name was Sven, Swedish for 
Swan, 

73 
Herb Gordon WIIBY 

P,S, In addition to telling you about Swan we'd naturally like to be selling 
you Swan — we have the works at regular prices. Look at the pictures in my 
competitors' ads, but send the orders to me. Hi ! 

HERBERT W.GORDON COMPANY 

Woodchuck HUl, Harvard, Mass., 01451 

Telephone 6 1 7-456-3548 



OCTOBER 1966 



B 



^mm 



m^ 



Ralph Hanno W8QUR 
3023 Emmick Drive 
Toledo, Ohio 43606 
Photos: Les Toth 




WRL Duo-Bander 84 



For a long time I have been spoiled by 
using a transceiver in the car and the boat, to 
the point where the transceiver was always 
being taken into the hotise. The separate trans- 
jtiitter and receiver were such tliat it was im- 
possilile to make into a transceiver combina- 
tion, When Woj'ld Radio Labs announced the 




Duobander 84 at its low price this seemed to 
be an ideal way to eliminate taking the rig 
out of the car and hauling it into the house 
ur, if it was on the boat, hauling the set and 
the AC power supply from the boat to the 
car and then into the house* 

The specs in tlie ad seemed too good to be- 
lieve for the money (only $159,95), but one 
was ordered* It is sometimes more fun to order 
and wait, than to buy off the shelf. This way 
you get double pleasure; first, the placing of 
the order, then the anticipation while waiting 
lor it to arrive. 

As soon as it arrived it had to be put on 
the air and, in spite of a large card on top of 
the set saying 'please read tlie instructions 
before you send it up in smoke," I had to 
hook it up and see how the receiver worked. 
80 meters was tried first, and the velvet- 
smooth dial and the wide 2 kHx divisions 
were a real pleasure to use. 

The urge to transmit was great, but I de- 
cided at this point that 1 was not as smart as 
tlie book— so the instiuctions were followed, 
and it was on the air in a few minutes. The 
luneup was the ultimate of simplicity: Adjust 
the bias; time; null the carrier and set the mic 
gain (with the aid of the large edge reading 
meter); then go. The 300 watts PEP sure 



74 



73 MAGAZINE 



looked big on the monftor scope and from the 
reports it looked big on tlie other fellow^s 
S-meter. 

The next step was to start studying the in- 
strtiction book to see where all tins signal was 
coming from and how it was being produced. 
At the same time the top and bottom of the 
set were removed for a good look inside. The 
first impression was that here was a very nice 
piece of workmanship, a layout that would be 
easy to service, and that all the parts were 
first line quaUty merchandise; no skimping 
here. 

The study of tlie instruction manual re- 
vealed that there were seven transistors, nine 
tubes and four diodes. An interesting thing 
here is that two of the diodes are actually 
transistors and are being used just like 
K9VXL says to do in the July 1966 issue of 
73 Magazine, All of the transistors are the 
same t>Tpej so if you like to have spares you 
onJv need one. 

As is standard with any sideband equip- 
ment, tliis transceiver is of the mixing type. 
The choice of frequencies is a good one. First 
the tumable oscillator is quite low ( 1.55 MHz 
to 1,75 MHz) wliich, with the use of transis- 
tors, makes a very stable oscillator. Now since 
this is a set that works on 75 and 40 meters, 
it can quickly be seen that the riglit choice of 
if frequency would allow the oscillator fre- 
quency to be added to get on 40 nieters and 
subtracted on 75 meters. The if frequency is 
5,5 MHz. The use of a McCoy 4 crystal lat- 
tice filter gives the desired selectivity and un- 
wanted sideband rejection, 

A very clever band switching airangement 
has been worked out using slide switches, A 
bar wdth fingers moves the three slide switches 
from 75 to 40 meters. This method of switch- 
ing allows very short leads, and then there is 
a space savings. 

Since tliis transceiver only tunes 200 kHz, 
the band pass tuning coils are slightly broad- 
banded so that tliey do not need to be tuned 
when going from one end of the band to the 
other. The coils are shunted with resistors and 
a portion of the coil is shorted out when going 
to 40 meters. Each stage has two coils so that 
the hand pass can be fairK' wide with steep 
enough sides to eliminate haiTnonics and spuri- 
ous radiation. 

One thing that impressed me was the fact 
that the parts list showed prices. This in itself 
is not so special, but liere all the prices are 
shown even for special items— and the prices 
are net and not iuflated prices. These prices 
are the same that you would pay in any radio 
store- And the prices of the special items like 




The final amplifier uses a pair of 6HF5's. 
These tubes liave a very high plate dissipa- 
tion to start with, and Sylvania tells us that m 
amateui- service tliey can be up-graded 30% 
to a total of 36 watts* These tubes also have 
the advantage that they will handle a fantas- 
tic amount of current because of the design of 
the plates. If you check the tube manual you 
will find that these tubes will handle 900 volts 
at an average cathode current of 315 mA 
which comes out over 280 watts each, so they 
just loaf along with only 300 watts PEP on 
two of them* 

To really find out what this new transceiver 
was doing, Ray Abair K8NBQ and I took it 
over to Rowe Industries to check it out with 
all the nice test gear that they have. Here is 
wliat we found, using a single tone signal at 
2000 Hz: 



Transmitter: 

Power output 
Carrier syppression 
Unwanted sideband 
spurious output 
(2tonesigJ 
Oscillator drift 

Receiver; 

Sensitivity 
Selectivity 



160 watts PEP 

43 dB below peak output 

41 dB below peak output 

29 dB below peak output 
Negligible 



0,45 liV for 10 dB S/N 
2.7 kHz at 6 dB down 
6 kHz at 60 dB do\%Ti 
43 dB 



Image & if rejection: 

The picture shows the small size of this 
transcei^ er which should make it a swell rig 
for mobile work. The small size wiU allow it 
to fit into the car in several ways* Dollar for 
dollar, you will have to look a long way io 
find so much transceiver for under $160; and 
it comes ready to operate. Just a little over 

50 ^^ a watt. 

. W8QUR 



* B 



OCTOBER 1966 



75 




NEW 




ONLY 10% DOWN 

OR TRADE-IN EQUIPMENT 

AT EDWARDS YOU 
GET: 

BIG TRADE-INS 

NO FINANCE CHARGE if 
balance paid within 
90 days 



350 



TRANSCEIVER 





5 BANDS I 

400 WATTSlI 



$420 



OTHER FEATURES 

3.5 - 4.0 mc, 7.0 - 7.5 mc, 13.85 - 14.35 mc, 
21.0 • 21.5 mc, 28.5 - 29.0 mc (10 meter full 
coverage kit available). 

I Transistorized VFO. 

» Crystal lattice filter. 

' ALC . . . AGC. . . SMeter. 

' 5Vz in. high, 13 in. wide, 11 in. deep, 

> 400 watts SSB input. 

> Lower sideband on 80M and 40M. Upper sideband 
on 20M, 15M, and lOM. (Opposite sideband kit 

available.) 




ACCESSORIES: 

• SW-117XC AC P/S 

• SW-14-117 DC P/S 

• SW-14X DC Module 



VX 1 vox Unit 



S 95 
130 

65 

35 



'4dl'*4 I ■'••■-i ¥ * » ■■«i«^4" P«¥l**4#i^ -4"*^-"i-«*i 




A 
LARGE SELECTION 

OF 
RECONDITIONED 



EQUIPMENT . . . 
INQUIRE. 

FASTEST DELIVERY 
TO ALL POINTS! 











L E CTR O N 



TELEPHONE POrter 2^8759 / 1320 19th ST. / LUBBOCK, TEXAS 79401 




7e 



73 MAGAZINE 




TIME PAYMENT PLAN 

Pay as little as 10% down or use your trade in as a down payment, 
remaining balance may be paid over a period of up to 36 months, 
finance charge if paid within 90 days. 

LARGEST SELECTION 



The 
No 



Edwards has the largest selection of new amateur equipment in the South- 
west. Drake, Swan, Galaxy, SBE, National, Hy-Gain, New Tronlcs and 
ail the rest are always on hand for immediate delivery. 

QUICK DELIVERY 

Our central location enables us to give the fastest delivery. Excellent freight 
and express connections mean you receive your equipment sooner. 

TRADE-INS 

We need your trade in. We have a ready market for reconditioned equip- 
ment. Top trade ins for your present equipment. We need late model 
transmitters, receivers^ and transceivers. Send today for a quote. 

RECONDITIONED EQUIPMENT 

Over 250 different types of reconditioned amateur equipment are available. 
Each item is thoroughly checked out and placed in top condition before 
being made available for sale. All equipment is guaranteed for 30 days. 

EXPORT ORDERS 

Write our export department for special price quotations. We are ready 
to ship equipment anywhere in the world. Special prices for the DX 
operator. 











L E CT R O N 



TELEPHONE POrter 2-8759 / 1320 19th ST. / LUBBOCK, TEXAS 79401 



i 



OCTOBER 1966 



77 



Dovid Large K7DEP 
Rt. 3, Box 384AA 
South White Road 
Son Jose, California 




RF Discriminator 



Here are some useful applications for a little-known circuit. 



The rf discriminator is potentially one of 
the most useful of receiving accessories. Un- 
fortunately, its use among hams, other than in 
an occasional VHF-FM receiver, is rare. This 
may be due to the lack of information avail- 
able ill amateur publications on the possibili- 
ties offered by this device. Some of these 
applications as a recei\ing aid for modes other 
than FM will be discussed here. Rather than 
go into details of operation or construction, 
v\ hich are adequately co\ ered elsewhere, *► ^' ^ 
this article will be concerned only with some 
of the wide variety of appUcations to which a 
disc rim hi a tor can be adapted. 

Perhaps the greatest use of this circuit is as 
a ^locking" device to keep a station centered 
in the receiver passband. Fig, 1 is a block 
diagram for this application. With the VFO 
tuned so that a signal is centered, the dis- 
criminator output is zero. If either the VFO 
or the applied rf signal tends to drift, the 
discriminator output applies a correction volt- 
age to the VFO (wliich must be equipped 
with a varactor or similar electronic tuning 
capabijitv ) which tends to correct for the drift. 
The extent to which the correction is made 
depends on the slope of tlie discriminator 
characteristic and the sensiti\ it\r of the VFO. 




/• 



whe 



re: 



Af^ = Afi/(1 + KA) 
Afi is the change in rf frequency 
applied 

Afo is the resulting change at the if 
frequency 

K is the slope of the discriminator 
characteristic in volts/kHz 
A is the electronic tuning sensi- 
tivity of the VFO in kHz/volts 
Fig, 2 is the circuit of the liniiter-discrimina- 
tor (designed by WA6BLX) in use here. The 
two stages of gain preceding the output stage 
insure that V4 rims completely drive-saturated 
class C, and thus is AM-insensitive. The 
measured limiting threshold of this circuit is 
about 10 mV. With tlie transformer and 
voltages sho\TO, die measured slope of the 



output cni^e is 2*4 volts/kHz- The dc varactor 
voltage must be sufficient to insure that the 
varactor is alwavs reverse biased and both that 
voltage and the plate voltage must be well 
regulated, since either \\ill modulate the out- 
put, S| allows the voltage fed to the varactor 
to be filtered to any degree desired independ- 
ently of tlie other outputs. 

Fig. 3 shows the common way to provide 
for varactor frequency modulation of an oscil- 
lator. It is far less cumbersome tlian a react* 
ance-tube modulator and has the capability of 
far liigher deviation sensitivity. The exact 
sensitivity can be varied by varving the bias 
voltage, the coupling capacitance C(., or the 
varactor.* The particular circuit in use at 
K7DEP has a sensitivitv^ of about 10 kH^voIt 
at 3 volts bias and this figure will be used in 
the examples belovv\ 

111 its most basic application, this circuit is a 
very^ good NBFM detector. Running open 
loop (S2 in Fig. 1 open) it will give 2 volts 
nns audio for a L5 kHz deviation. 

In the VHF bands, wide-band FM does 
enjoy some deserved popularity: Modulation is 
a low-level process, signal generation is easier 
than for SSB^ and all amplifier stages run at 
class C efficiency. The problem is reception, 
which requires a wide if bandwdth and wide 
discriminator. If, however, we close the loop 




OUT 



MODULATION 
OUTMJT 



Fig. 1 Block diagram of a simple locking (auto- 
matic frequency control) system for a receiver. 



7a 



73 MAGAZINE 



with a correction signal which will follow the 
instantaneous carrier frequency, the modula- 
tion will be effectively narrow cd by the factor 
1/(K + KA) as calculated above (about 25 
for the circuit discussed). Thus a 12.5 kHz 
deviation FM signal is reduced to 0,5 kHz in 
the if strip and to about 0.3 volts rms of audio 
at the FM output. Also, since the discrimina- 
tor is dc coupled to the varactor, any long-term 
drift of either receiver or carrier will be re- 
duced by the same factor as the modulation. 
Xute that the same discriminator performs all 
three functions of bandwidth reduction, fre- 
quency locking, and detection simultaneously* 

The problem of carrier and local oscillator 
stability becomes more serious as frequency 
increases. This is especially true of receivers 
which time entire VHF bands in one pass. 
With a 10-13 kHz bandwidth, a little drift isn't 
too noticeable, but with a 500 Hz CW filter it 
can be disastrous! By running closed loop, we 
can easily reduce the drift to almost any de- 
gree desired. By employing a very long time 
constant in the correctioji si^al path, loss of 
lock between CW characters can be avoided. 
All tliis allows the use of neai-optimum if 
bandwidths for AM, CW, and, as we shall see, 
possibly even SSB, 

For the serious VHF*er for whom stabilitv 
is no problem, the discriminator offers an 
added bonus in measuring doppler sliifts. By 
running open loop and monitoring the dc out- 
put on a VTAM (or better still on a chart 
recorder) 30 Hz of carrier shift can easil>^ be 
read. Since observed shifts on OSCAR have 
been of the order of 6 kHz^ this is adequate 
for most work. If a chart recorder having a dc 



COhfTROL 

VOLTAGE 

INPUT 



RFC 



Cc 




\H 






J (X I) 



-OTO REST 

OF OSCILLATOR 



WOflMAL TiNfNG 
CARACJTOaS 



Fig, 2. The limiter-discriminator designed by 
WA6BLX used by K7DEP, It will keep your re- 
ceiver tuned to the station you're working even 
though the other station drifts slightly across the 
band, 

offset capabiHty is used, then even greater 
sensitivity' is possible. 

In a completely different field of interest, 
the rf discriminator provides one of tlie easier, 
though admittedly not one of the best, ways 
of receiving RTTY* Running open loop, the 
discriminator in Fig. 2 puts out just over two 
volts difference in dc level from space to 
mark with standard 850 Hz shfft. This could 
be used to drive a keying tube directly or, for 
better reliability, used to switch a Schmitt 
trigger^j and that in turn could drive a keyer 
ill the machine local loop. A very simple 
arrangement of this t>T7e could be a realistic 
answer to the casual RTTY operator who 
doesn't want to invest the time it takes to 
build a complete audio converter-terminal 
unit. Licidentally, if a single VFO is used for 
receiving and transmitting, as is becoming 
increasingly common today, tlieii that varactor 
is already there for FSK transmission, requir- 
ing less than OJ volts drive for 850 Hz sliift. 

Another possible use for the discriminator, 
and the one where it is needed most, is as a 
SSB tuning aid. With one of the better re- 
ceivers now on the market, it is relatively easy 



MILLER 12-C2 



455 KHi 
iHp-lST 



rn 




6 



30 m4 



TO VAflACTOR 

m VFO 



Fig. 3- The common varactor frequency control 
that is applied to transmitter or receiver VFO's, 



AC 

CXJTPLFT 



OC 
OUTR/T 



OCTOBER l%S 



79 



SIOEEAND : IQV HfAS 
CARRIER : ^IV RMS 



SSB 



IN 




COflRECTlOW 
SIGNAL 



* sideband: C.OOIV RMS 
CARREER : JOO! TO .003 V RMS 



CARRaER 
.3V RMS 



Fig. 4. Correction system to keep SSB stations 
tuned in properly. This is especially nice in round 
tobies. 

to tiine sideband to readable fidelity. But for 
truly natural sounding speech, the reinserted 
carrier must be within 10 Hz ot the sup- 
pressed carrier.*^ Not only is this difficult, but 
with more than two stations in the QSO, it 
requires constant BFO jugghng. 

The system in common commercial use 
separates the suppressed carrier from its side- 
band and re-aniplLBes it to a usable level 
Then it is fed to the discriminator which pro- 
vides a correction signal to tlie VFO to ^lock" 
the receiver on the carrier as described above. 
All this will requii^e two additional compo- 
nents besides the basic limiter-discriminator. 
The first is a sharp filter detuned slightly from 
the [/ center frequency (assmuing that the 
sideband is centered), and the second is some 



additional amplification between the filter and 
limxter stages. More specifically^ if we assume 
that the received carrier is 60 dB below the 
average sideband level at the if output (this 
may seem pessimistic, but remember that the 
carrier may be part way down the skirt of the 
// characteristic), then the sharp filter should 
be at least 60 dB down at twice the lowest 
audio frequency transmitted (usually 300 Hz). 
The additional amplification is to elevate the 
carrier to well over the limiting threshold. 
Two stages of gain should be sufficient Fig. 4 
shows this process. Since the only critical com- 
ponent is the shaip filter, this system is quite 
feasible for ham use. Using this mode of 
operaHon, several stations in a single QSO 
will all lock if thev are within ± 250 Hz. Also, 
since 10 Hz is below the limit of most receiver 
audio systems, easy exalted carrier reception 
of AM is provided for under the same condi- 
tions as SSB^ but without the necessit\^ of the 
extra amplification and filtering. 

A lot of fuss and bother that isn't really 
necessar\? Perhaps, but that is what makes 
the difference between "good enough for 
amateur*' and truly professional qualitv. 

, . , K7DEP 



^ **SpeciaIi2ed Communications Systems/^ ARBL Hand- 
biKik. 1961, p. 329-330, 

s Allen Rata, 'TJHT Roundup," CQ f April, 1S64), 79-80. 

* Ralph W, Burhflns, "An IF Trackinfir Filter for 
Weak-Signal Reception,*' QST (September, 11164) 11^17, 
1G6, 

* R» E, Baird« "Something New in Frequency Modula- 
tiOD," 71, (October, 1960), 10-11- 

^ Jim Kyle, '*Uiiderstandiri|f the Schmitt Trigger Cir- 
cuit," 73, (March. 1965) 74-78, 

* Terman, Frederick E.* EleetTonic and Radio Eng^i- 
neering, (New York, 1955) pp. 957-958, 



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80 



73 MAGAZINE 



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OCTOBER IM6 



81 




Bob Boird W7CSD 
Chairman Electronics Department 
Oregon Technical Institute 
Klamath Falls, Oregon 



Amplitude Modulation 

vs. the Carrier 



Some easy'tO'iinderstand proof that 
a carrier is not affected by amplitude modulation. 



The statement is often made in the study of 
amplitude modulation that the actual carrier 
does not change in amplitude during the mod- 
ulation process* Many an old time AM ham 
will raise his eyebrows in horror; however the 
statement is true. We have all looked at the 
pattern of modulation on an oscilloscope using 
a linear sweep* It 100% prevails we note that 
the pattern varies from zero amplitude on 
100% negative peaks to twice tlie amplitude of 
the carrier at 100% positive peaks. Hence the 
carrier amplitude varies • Tain't so chum! You 
forgot what you were looking at and what the 
oscilloscope sees. The oscilloscope sees the 
complete rl' signul. And the complete rf signal 
is made up of a carrier and two sidebands. 
The scope sees them all at once and gives you 
the composite picture. If you had a very selec- 
tive circuit that would tune in the earlier and 
reject the sidebands you cuiild look at the car- 
rier all by itself. What you w^onld see would 
be a nice smooth cairier that does not change 
in amplitude no matter where )0u set the 
modulation vokime control. 

At about this point in the discussion some 
joker in crowd says, "What will happen if you 




over-modulate and a 100% negative peak is 
maintained over a considerable period of time? 
Since there is no power during this period 
there can be no carrier. Surely this is too long 
a time for the flywheel of the tank circuit to 
maintain the carrier without damping out." 
Well believe it or not the original statement is 
still true. The carrier is still there and does not 
vary in amphtnde during the process of mod- 
ulation. This is a vt i\ difficult thing to explain 
physically. Let us try and see if we can ex- 
plain this seemingly impossible situation. 

First of all let us hasten to agree that the 
flywheel clluct will damp out very rapidly if a 
circuit is loaded at all. Fig. 1 is an oscillo- 
scope pattern of the output of a frequency 
tripler which is loaded to some extent. There 
is a plate ctirrent pulse every tliird cycle. It is 
evident tliat even in three rf cycles the degree 
of damping is quite measurable, SecondlVt the 
decision was made to set up the worst possible 
example of negative peak modulation possible, 
and observe the results. Therefore a demon- 
stration type rf amplifier driven by a crystal 
oscillator was adjusted so that it would be di- 




Fig, L Output of a frequency tripler. 



Fig, 2. Entire experimental set up. 



S2 



73 MAGAZINE 




Fig. 3. Upper-modulation pattern from transmit- 
ter. Lower-carrier pattern (455 kHz) observed on 
HQ 160 receiver. Both viewed simuftoneouslv- 
Moire on corrier caused by double pattern on 
scope. 




Fig. 4, Same as Fig. 3, but with less modulation, 
Note constant carrier amplitude in Figs. 3, 4 and 5, 




Fig. 5. Some as Figs, 3 and 4, but with less modu- 
I at ion • 

rect modulated by a square w^ve generator. 
The signal was picked up by a Hammarland 
HQ 160 receiver sufficiently isolated from the 
crystal oscillator so that the carrier of the 
amplifier as observed at the 455 kHz if was 
much larger than that of the oscillator. The 
if of the HQ 160 Was fed into a Tektronix 545 
scope. Using 10 kHz square wave audio as a 
modulating signal, it is possible to observe the 

OCTOBER 1966 



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Fig, 6, Upper sideband, corrier and lower sideband- 
Taken in three exposures* Pattern moved and HQ 
160 tuned for each exposure. See text. 



carriei* without either sideband or to observe 
either sideband without the presence of the 
carrier or the other sideband, when the re- 
ceiver is adjusted to its sharp tuning pc^sition. 
The complete setup is pictured in Fig. 2. 

Fig- 3 shows the modulation pattern coming 
out of the modulated amplifier, in the top por- 
tion, while the bottom pattern displays the 
carrier simultaneously (as view^ed at the 455 
kHz if) tuned in on the recei\'er. These two 
patterns were scoped simultaneously with the 
scope being triggered on the square wave. 
This results in a noticeable moire effect on the 
carrier display which disappears if the carrier 
is viewed without the second pattem being 
present on the scope. It should be pointed out 
that the period of nothing but center line ia 
Fig. 3 is on the order of 40 microseconds* 
Since die carrier frequency is about 4 MHz 
this would amount to time for 160 rf cycles, 
much longer than the flywheel could possibly 
maintain the oscillation of the tank circuit. 
So the carrier is ready there! As can be seen 
from the figure the ampMtude of the carrier 
does not change during modulation nor does it 
come in bursts, Fig» 4 and 5 show the same 
conditions at less than 1CM)% modulation. (Am- 
pUtude was adjusted at the scope to give the 
right size for making pictures). Fig. 6 shows 
the upper sideband, the carrier and the lower 
sideband with the time base on the scope so 
that von can see the indi\idual rf cveles. Note 
the nice wave shape and no evidence of damp- 



ing. The picture w^as taken as a triple exposure 
rather than simultaneously. The upper side- 
band was tuned in first on the HQ 160 and po- 
sitioned in the upper third of the scope, then 
snapped. The carrier was then tuned in and 
positioned in the center and snapped. Lastly 
the lower sideband was taken. So the pictures 
do not represent a siuiultaneous action and 
the relative phase is meaningless. They all 
look alike because a half dozen cycles of 3980 
kHz practically match a half do?.en cycles of 
3990 or 4000 kHz. If you look at either side- 
band by itself and var>^ the modulation, of 
course ttie amplitude changes. With no mod- 
ulation there will be no sideband at all and it 
will increase in amplitude as the gain is turned 
up. The carrier when \1ewed alone changes 
not at all regardless of w^here you set the gain 

control. 

Non-mathematical explanation: It is true 
that during the negative peak we do have a 
total of zero power. But the factors that add 
up to zero are not zero themselves* The car- 
rier is one of these factors. Also even those not 
mathematically inclined w^ill agree that a 
square wave or any distorted wave can be 
broken do\\Tti into a series of sine waves. Any- 
body who has ever operated a wave anal>^er 
knows this. So why should a square wave yield 
anything different than multiple sine wave 
modulation? Don't forget the oscinosci>pe sees 
all of these frequencies at once when con- 
nected to the modulated stage and shows you 
the composite sum. 

An interesting observation: A side observa- 
tion of this experiment with square wave mod- 
ulation with the carrier frequency of 3990 
kHz w^as that it was possible to observ^e side- 
bands every 10 kHz for at least 400 kHz 
either side of 3990, This was a very impres- 
sive demonstration of why overmodulation 
causes *1>uck shot" the width of the band. 

Once again J the amplitude of the carrier 
does not vary with amplitude modulation. The 
amplitude of the entire signal (composed of 
carrier and sidebands) does vary from zero to 
twice the amplitude of the carrier by itself 
with 1005& modulation, 

Hope this doesn't give you old time AM 
boys a nightmare! 

. . , W7CSD 



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84 



73 MAGAZIKE 




For the average amateur located on a small city lot, the prob- 
lem of an adequate low-cost beam antenna system has never 
been properly solved. Now Henry Radio has exercised its 
unique experience and buying capacity to break the antenna 
barrier. Here is a complete antenna program pre-engineered, 
pre-matched and pre-packaged to suit the average QTH and 
the average pocket-book. 



Package No. HR-1 

Trtstao CZ337 New concept 40 
ft, crank-up tower 
100 ft, RG-58U Coax 
CDR TR-44 Rotator 
Hornet TB 500B Three ele- 
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100 ft. control cable 
The perfect answer for the 
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Tristao CZ454 New concept 
crank- up tower 
CDR TR-44 Rotator 
Hornet TB-500-4 Three ele- 
ment trt-band beam 
100 ft. RG-58U Coax 
100 ft. control cable 
For the medium power DX*er 
who wants to work them bare- 
foot. Regularly $500 plus 
approx, $25 freight, a $525 
value. Our package price 
$425.00 (freight prepaid to 
your door). 



Package No. ffR-3 • Tristao C2 454 New concept 60 ft, crank-up 
tower • 100 ft, RG-SU Coax ■ CDR Ham-M Heavy duty rotator - 
Hornet TB-1000'4 Three element tri-band beam * 100 ft. control 
cable " Here is our masterpiece. The right combination of antenna 
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OCTOBER 196« 



85 




NEW PRODUCTS 




Revised Second OP 

Band conditions are improving every day, 
and Electro- Voice has just published the new, 
f ally -revised, fourth edition of WOIOP's Second 
Op, This well-known operating aid of durable, 
laminated card stock is actuaUy a simple DX 
computer providing vital data such as beam 
headings, identification of prefixes, time zone, 
continent, and postage rates* Included also on 
the periphery of each Second Op are pro- 
visions for logging contacts and receipt of con- 
firmation. You can get your new Second Op 
for $i from Electro- Voice, Department PR-73, 
Buchanan, Michigan or from your Electio- 
Voice dealer. 







Super *'Q'' Roto-V Antenna 

Super *'Q" Products has just brought out a 
rotatable inverted V antenna for 15 or 20 
meter operation. It is constructed from alumi- 
num tubing with telescoping end sections so 
that it can be used on either 14 or 21 MHz. 
The manufacturer states that when the an* 
tenna is tuned up for operation on 14.275 
with an SWR of 1:1, the SWR at 14.350 is 
not greater than 1.3:1. Since the input im- 
pedance of this antenna is 50 ohms, it can 
be fed directly with RG-8/U coaxial line and 
no matching devices are needed. The light- 



weight construction of this antenna features 
heavy polystyrene insulators which hold the 
tubing in the proper position and clamps that 
will fit any mast up to IK inches in diameter. 
The radiation pattera is bi-directional and 
attenuation off the sides of the antenna is 
approxiamtely 15 dB, The low center of 
gravity of this design and its light weight 
simpliiSes the problem of rotation since a 
small, light-duty TV rotator is more than ade- 
quate. Tests in vnndstorms have shown no 
signs af strain in winds up to 75 mph. The 
Roto-V is available express or tmck freight 
collect for $29.95 from Super ''Q" Products, 
Box 8405, 5704 South Staples, Cotijus Christi, 
Texas 78413. 




Lafayette 

HA-500 

Ham Receiver 



The new Lafayette HA-500 ham band re- 
ceiver tunes the 80 through 6 meter amateur 
bands in six tuning ranges. It's a 10-tube 
double conversion superheterodvTie. Among its 
features are tuned rf and first mixers, two 
mechanical filters, product detection, "always- 
on'' oscillator filament, built-in 100 kHz cali- 
brator, illuminated slide-rule dial, S-meter, 
automatically switched AGC for AM or SSB, 
and less than 1 mV sensitivity. Size: 15" W x 
7r H X 10'' D. Price is $149.95. Write 
Lafayette for more information at 111 Jericho 
Turnpike, Syosset, L.L, N.Y, 11791. 



Heath SB-610 
Monitor Scope 




The newest member of the Heath SB*Series 
is the Heathkit SB-610 Signal Monitor for both 
transmitted and received signals. It displays 
actual signal envelopes or trapezoid patterns 
from transmitters, and it wiU give an equally 
complete picture of signals being received. It 
can be used with low or high power trans- 
mitters from 160 to 6 meters and with receiver 
ifs as high as 6 MHz. Price is $69.95. You 
can get complete information on the SB-610 
from Heath Company, Benton Harbor, Michi- 
gan 49022. 



86 



73 MAGAZINE 




Trans- Key Electronic Keyer 

The new Traiis-Key traiiiiijitorizecl elecbonic 
keyer offers either automatic (self-completing 
dots and dashes) or semi-automatic or *T3Ug" 
operation (not-self-conipleting). This unit is 
completely battery powered and doe^ not re- 
quire connection to 110 volt lines. It has relay 
output so there are no worries about voltage 
polarity or method of keying your tiansmitter 
further, it is fully adjustable from a few words 
per minute to over 50 words per minute and 
features an adjustable dot-space ratio. Since 
it only requires 10 to 15 mils of current, the 
battery supply has a very long life. $29.50 
from your local distributor or write to W6PHA, 
Global Import Company, l^nx 246, El Toro, 
California. 



Motorola IC Projects 

Integrated circuits (IC's) are finding rapid 
acceptance and varied application in industry 
today. The new book Integrated Circuit Proj- 
ects From Motorola brings these useful devices 
into the grasp of hobbyists and experimenters. 
Because integrated circuits are the basic com- 
ponent of each project, the book begins with 
a brief explanation of IC theory and a defini- 
tion of terms. The second chapter includes 
construction techniques and a pin location 
chart for those not familiar with sohd state 
components. Six projects are fully described 
Including, among others, an electronic organ, 
a binary computer, and a square wave gener- 
ator. Each project begins with a brief circuit 
description, lists all the parts needed, and 
leads the builder through a step by step con- 
struction of the project. Schematics and draw- 
ings of the recommended layout are included 
as an aid to the builder. Testing and operation 
procedures complete each presentation. Availa- 
ble for $1 from your local Motorola HEP 
distributor. Motorola, Inc., Box 955, Phoenix, 
Ariz. 85001. 

Motorola Solid State Projects 

Eight projects for hams and experimenters 
are collected in the new book. Solid State 
Projects From Motorola. Hams might like to 
build such projects as a deluxe CPO, audio 

OCTOBER 1966 



signal generator, regulated ten volt power 
supply, or six meter converter. Experimenters 
might enjoy duplicating the panic button, 
mini-fi h-ansistor amplifier, intercom system, or 
motor speed control. All are clearly and com- 
pletely described. Each project includes pic- 
tures of the finished product, layout diagrams 
and schematics, as well as a complete parts 
list. The projects are described in enough de- 
tail that even the beginner to electronics could 
complete them. To help those not familiar 
with the workings of semiconductors, a cliapter 
at the beginning of the book provides basic 
theory. If one has not soldered semiconductors 
before, or isn't sure of the correct pin con- 
nections, he has no cause for alarm, as both 
are covered in the chapter on builder's hints. 
All use Motorola HEP transistors. The manual 
is available for just 50^ from local HEP 
dealer. Motorola HEP Program, Box 955, 
Phoenix, Arizona 85001. 

RCA Linear IC Handbook 

RCA has just released a new book concern- 
ing IC design and apphcations entitled RCA 
Linear Integrated Circuit Vundamentals. This 
new manual, the first of its Idnd in the indus- 
try, is written primarily for equipment and 
system designers, but is of interest to anyone 
concerned with this new field in electronics. 
The first chapter is about general design con- 
siderations followed by basic configuration of 
the Knear IC and of the operational-amphfier, 
and finally chaiacteristics and applications of 
IC's. In the last chapter (applications) the 
basic family of IC's (differential amplifiers) 
is fully described. Dc, audio, video, if, rf, and 
operational amplifiers are covered. This last 
chapter includes more than half of the book, 
and appears to be the section most likely to 
be referred to by hams. Circuit diagrams, op- 
erating characteristics and performance data 
are liberally included throughout. Hams in- 
terested in keeping abreast of this rapidly ex- 
panding field would do well to invest $2 m 
this fact-packed book. Copies may be obtained 
from RCA distributors, or from Commercial 
Engineering, RC.\ Elecbronic Components and 
Devices, Harrison, N. J. 07029. 

Motorola Microwave Designer's Data 

Designers who work with microwave should 
make sure that they get Motorola's Microwave 
Designer's Data Manual. It contains applica- 
tion notes and spec sheets on Motorola Epi- 
caps, varactors, and rf switches. Write on your 
company letterhead to Motorola. 

S7 





■^ 



PROPAGATION 



OCTOBER 



1966 



J. H. Nel son 



DX CALENDAR 



SUN MON TUE I WED THU 1 FRI SAT 




legend: 



HF 



1 



good fair poor 



VHF 




likely 



88 



73 MAGAZtNE 



OPTIMUM FREQUENCIES HOURLY 




EASTERN 



UNITED 



STATES 



TO: 



ALASKA 



ARGENTINA 



AUSTRALIA 



CANAL ZONE 



ENGLAND 



HAWAtI 



INDIA 



JAPAN 



MEXICO 




PHILIPPINES 



PUERTO RICO 



SOUTH AFRICA 



U.S.S.R. 



WEST COAST 



i 

I 



CENTRAL 



UNITED 



STATES 



TO: 



ALASKA 



ARGENTINA 



AUSTRALIA 



CANAL ZONE 



ENGLAND 



HAWAII 



INDIA 



JAPAN 



MEXICO 



PHILIPPINES 



U.S.S.R 




PUERTO RICO 



SOUTH AFRICA 



WESTERN 



UNITED 



STATES 



TO: 




Legend 




■ '.'T -'. _ r m< ■ ■ ■ a qi ■ ■ 
h r w m w m m a.f^a ■ i^-i 

t + ■■ ■ "J^i jJHp ■ -f -P + i 




^|l Very difficuft circuH this period 



Frequency in ^ Megahertz 



Next higher frequency may be 
useful this period 



OCTOBER 1966 



89 




Letters 



Oscillator Error 

Dear 73: 

Thi3 schematic of the six volt oscillator em page 40 of 
the August issue is in error. On P2* the plug for 12 V, 
there should l>e tio connection between pin two and the 
juniper cormectiiig pins one and three. The plug as shown 
in the article would l:iuni out the tul>e Elament a$ soon as 
it was cnimected. 

Don Marquardt K0SOA 
Gary J Indiana 

It Hertz 

Dear 73: 

I am not the type to go around complaining and pro- 
testing alK>yt everything: on principle. But every now 
and then something gets me quite upset and msikes me 
feel obligred to speak my piece. 

When 1 read in the May issue that you were convert- 
ings from cycles to herti, my reaction was '*He's joking ; 
or at least, he won*t start for about ten years." How- 
ever, having now looked through the June issue, 1 &ee 
that you mean business. And I would^ thereforef like to 
r^Kii^ter my cibjection. If you want to turn 73 into a 
crusade for international cooperation and unity, why 
stop with Hz? You should certainly use European ache- 
matic gym bo Ib and tube designations* and while you're 
at ft you could publish the whole magazine in E&peranto, 

Forgive the over-dramatization, but what I'm getting 
at IB this, OfTleial government policy notwIthBtanding, 
a switch from cps to H^ in n mag^i^ine like 73 should 
reject such a switch on the part of its readers ; it 
should not be done to try to extort such a switch from 
them. 

I am tS years old, and for the foreseeable future, I for 
one shall stick with good old cps, in writing and speak- 
ing, unless and until T be convinced that a change to 
Hz for internal American u^age has been about 95% 
accepted; at which time I would yield to the majority. 
I do not, however, believe that such a point has been 
reached, nor do I believe it to be the proper role of your 
magnsine to pugh it. 

When I see Hk, kHz and MHz in place of cps, kc and 
Mc* particularly in a strictly dfimeatie publication, let 
me tell you, it hertz, 

Alan Goott K31T0U 
Silver Spring, Md. 

Compliments 

Dear 73: 

Congratulations on your infonnative and intere«rtrng 
magazine. As an electrical engineer and buildrr of my own 
etiuipment, T am particularly enthusiastic abtmt your con* 
stniction articles. Tlioy incorporate *'state of the art" 
mc'thods in projects worthwhile to the amateur* 

I would like to see more reference type articles such as 
the one on coaxial transmission lines in the July issue. 
Gofwt work! 

Dean Farrish WB4DAS/DL5LW 
HDQf Seventh Army Signal Section 

Dear 73: 

July *6ft lasue — the mo8t diabolical coverCsV yet!! I 
pick the damn thing up upside down every time ! ! I 

And T won*t even mention Batham-^even upt^ide down : 
sick, sick I 

Swell solid wtate articlen, thouifh. You* re on the beam 
with the latest scoop in that department, 

Jobn Anslow WA6DPJ 
San Francbco» California 

The design u:(%«d in the rover is by WAlVAF and WA4- 
WOL. Bomehuiv that got left out of the July Lisue« Paul. 

Denr 73; 

My eumplimentts to yoxi for that April is^suo. Since we 
all read Playboy fwho doesn't) even the nt>n-ham^ get a 
laugh out of it. Keep up the excellent work. Even 
though we can't operate fnim here, your magazine is 
well read and discussed by quite a number of haniH, 
non-hams, technicians, tech reps, et«.» at this tcaation. 

Arv Evans K7HKL 
Viet Nam 



Dear 73: 

Just a quick note to congratulate you on the evolu- 
tionary path your magazine is taking. The vast number 
of articles per issue and the up-to-date subjects have, in 
my opinion, considerable appeal. Of great importance is 
the mix between construction artiolea ami information 
articles (origin of the code, explanation of ETTYL 
73 started out with an Image of "How to do it," but 
appears to be broadening lately. Good! For peters sake 
fellows, don't let it go ti>o far in any one direction. 

The April issue was partkulariy clever. The Playboy 
theme ia timely and was well satirized by KSSlJK's 
ilJustrations. 

Keep up the good work, 

A. Schechner 

Philadelphia, Pa. 



Micro-Ultima tic 

Dear 7Q: 

Since publication of the *"Micro-Ultimaiic*' article in 
your June issue, I have received quite a bit of corre- 
spondence and am pleased at the number of CW hams 
who have built the keyer. There are several questions 
many letters have in common. Also there are a few sug- 
gestions which 1 feel would aid in the construction and 
debugging of the keyer. Therefore I am writing to help 
those others who may not yet have written me. 

First, 1 must apologize for implying an identity in per- 
formanct* between the Micro- Ultimatic and Kaye's original 
Ultimatic back in 1955. Tliere is a hmdamental difference 
in performance between the two keyers, and that is this: 
With btvth key paddles dotied at the same time, tlie Micro- 
UFtimatie will generate a .string of alternate dots and 
dashes. This is normal. The 1955 Ultimatic does not 
respond the same way. 1 thank K6LTS for the question 
which brought this difference to light. 

An improvement in performance is had by laising the 
output capacitor in the power supply to about 1000 ^. 
With the 200 |iF in the original schematic, 120-Hz ripple 
was excessive and caused the pulse generator to tend to 
lock to subharmonics of the npple. This had the effect of 
making the keyer "^prefer" certain operating speeds* 

There seem to be no errors in the article as pubKshed. 
Several hams have written me to describe their success in 
hnildiug and operating the keyer* This is somewhat un- 
usual, since most letters would be from builders who are 
having trouble. 

It is quite important that no rf energy get into the 
Iceyer. The usual shielding and filtering practices are called 
for. Make sure that the kejing output to the transmitter is 
not a path for rf energy. A low-pass filter cut ling off 
around 100 Hx and mounted at the transmitter was re- 
quired in one stubborn case* 

A few cases of defective integrated circuits were re- 
ported. Fairchild makes a practice of replacing these dead- 
on-arrival units through their distributors at no charge, 
according to a friend of nrinc So the builder needn't 
despair if his $4.00 flip-flop doesn't work. The IC/s can 
he ruined however* by inadvertent application of B* to 
any output lead if the transistor is conducting at the time. 
So precautions eommon to any semiconductors are required. 
1 have just been advised by Fairchild that the prices 
on the epaxy micrologic used in the keyer ha\^e been 
greatly reduced, as follows: The 9923 flip-flop is now 
$1*50 J the 9914 gate, $0.80 in 1-24 lots. Tliis cuts the 
price of the TC's in tlae keyer by nearly two-thirds. This 
should be welcome news to those considering building the 
keyer. 

And finallv, I would be pleased to contact anyone using 
the Micro- Uitimatic on the air* 7060 kHz at 0100 GMT 
Wednesdavs Tin usually on. 

Tom Pickering, WICFW 
Portsmouth^ R. 1. 

Dear 7^1 

The article by WICF^V in the June 73 on the Miero- 
Ultimatic Keyer is worse than any O^T article ever pub- 
lished and as to reader interest, perhaps only one ham in 
the entire subscription list would be intereisted. Your arti- 
cles are too un in t ere siting ly tt*chnicaL One can buy a gt>od 
keyer cheaper than this complicated iobbie, 

James Russell WSBIT 
Fair\'iew Park» Ohio 



90 



73 MAGAZINE 



Sfx Meter Transmitting Converter 




Dear 73: 

Thay^bt I'd send along a photci of my 6 meter SSB 
transmittrng converter which I coastructed from your 
November issoe. D«sig:Tied by Joe Owings K0AHD. I 
found the rig worked excellently and no problems were 
encountered in constiiiction or ope rat in jr. Since March 
I have been a^si^rned oversea.^ and hold the call SVPWV 
and operate 20 meters mostly* 

Keep the fine articles coming 1 

Dick Searle, KlVWJ, SV0WV 

Government Support of Hams 

Mr, Stewart II, MacKenxie 
Huntin^on Bch,, California 
Dear Sir: 

This refers to your letter dated June 12, 1966, which 
requested inform at ion concerning the next international 
telecommunication conference, its substance and poten- 
tial impact on the freciuency bands allocated to the 
Amateur Radio Service* 

There has been a considerable amount of publicity 
during^ the past few years concerning the next inter- 
national telecomnnunication conference and the possi- 
bility that amateur frequencies may be reallocated to 
other services- This publicity haa been generated by and 
given extGHBive coveraj^e iii the national amateur radio 
mag-azines and periodicals and is an indirect result of 
the 1959 Geneva Telecommunication Conference which 
provided some frequencies In the 7 Mc/s amateur band 
for broadcasting in the African -European areas. 

The amateur frequencies established for the American 
continents at the internatiODal conference held in Wash- 
ington in 1927 have had only very minor modifications 
since that time. The United States proposals to the 
International radio conferences have always sought to 
maintain the alloeation of the amateur bands, and it is 
expected that future proposals wUl endeavor to continue 
this status- However, with the creation of new^ countries, 
there is a continuing demand for more frequency space 
for the requirements of these new nations. The amateur 
frequencies are fertile ground In which to exploit their 
ilemands and it is high 15^ improbable that such countries 
would be sympathetic to the am&tear cause until their 
needs are met. It is this factor, among others, that has 
brought forth widespread fear in the radio amateur 
circles that the next international conference might re- 
allocate segments of the amateur bands to other services. 
It is important to note, however, that a conference 
authorized to treat a subject such as this has not been 
scheduled and probably will not be for at least the next 
three or four years. If and when such a conference is 
called there is little likelihood that the United States 
will depart from its pro-amateur position- In any events 
the public wUl be afforded an opportunity to comment 
on the position developed by the United States for that 
eoaferenee* 

Ben F. Waple 

Secretary 

Federal Communications Commission 

Washington, DX. 20054 




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HANDBOOK 



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Kyle K5JKX, one of the out- 
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in the electronics field. The 
VHF Antenna Handbook 
covers complete theory and 
all E>ractical details for every 
type of VHF and UHF an- 
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the commercial antenna ca- 
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have this book* 

Price is $2 from 



TOPICS COVERED: 

Basic concepts 
Folded dipoie 
Slot ontenna 
Conicai antenna 
Coaxial antenna 
Holo antenna 
Abe Lincoln 
Turnstile antenna 
Ground plone 

antenna 
Broodside phosed 

array 
Endfire phosed array 
Mattress orroy 
Sterba curtptn 
ZL special 

Long and short yag^s 
Weeping willow 
Quad antenna 
Helix 

Cross beam 
Circular quod 
Transmission line 

antenna 
Long wire 
V antenna 
Rhombic ontenno 
Log periodic 
Horn antenna 
Di scone ontenna 
Comer reflector 

Trough 
Paraboloid 
Plane reflector 
Backfire 
Cyiindrical 

parobolo 
Procticol 

construction 
Mounts 
And much more 



73 Magazine, Peterborough, N.H. 03458 



^^ 



IMPORTANT NOTICE 

We've hod to revise our subscription list to satisfy the 
new Post Office reguiations, Now oil of our stencil^' 
are filed by Zip Codes. We can't find your oddress 
without your Zip Code, so please include it with oil 
cofrespondence. 



RSGB Handbooks 

Dear 73: 

About two week.*! ago I received the RSGB Data Refer- 
ence Book, and a day or t^vo Ago received the Amateur 
Radio Handlxjok. I still have to receive the RSGB Amateur 
Radio Circuits Book, which I assume is still out of stock? 
iyes} I am pleased with the British books and hope the 
other one is forthcoming soon* My best wshes for con- 
tinued success of *l5-\ You give the hams the meaty 

artides they want and not a lot of contest, etc, ^^^.„,^ 

H, F. Happoldt, K31PV 

liaverforda Fa. 

Dear 73: 

I have subscribed to the 73 magazine for the past 
couple of years and articles have appeared from time to 
time regarding the FCC, though to my knowledge there 
has lieea no mention of consideration to the old tried and 
true AM amateiu- stations stiO trv'ing to enjoy the privilege 
of operating only to be washed by the unnecessary splatter 
of sideband operation killing the use of ten to fifteen kc 
of the band which coidd be used by perhaps four or five 
AM stations [not at once. Ed J* 

What I am asking of you is if a poll of some kind 
could l>e gotten in favor of consideration to AM and sub- 
mitted to FCC so there could be a bit of protection for 
the old and reKable type of transmission. 

I would be ver>' happy to help on any reasonable sug- 
gestion to help and preserve the use of -^JNl to better 
advantage. 

Thank you very kindly. 

Claude Keneaster WA5LFL 

El Paso, Texas 



OCTOBIR 1966 



91 



Build the modern, easy way with 
circuit boards and solid state! 




WlJJL*s code pmctkc oscillator^monitor described in Llie 
July *65 ?3 belongs io every shack and sliack*to-be. It's 
inexpensive and works well. The drilled board wilh all 

components locations marked is only $L The board with 
the parts mounted on it h |3. Or you can buy it mounted 
in an attractive case as shown abovcj complete wilh 
battery, for |7.9S» 







Here*s an excellent field strength meter. It's easy lo u^e 
with a built-in amplifier for use with any 1 mA meter. 
See the article in the December *6S 73. The drilled 
screened board is $1, With the components mounted it*s 
S3. Complete in an attract tve case, the price is only 

A good HF-VHF SWR bridge do^D't have lo cost a lot. 
You can make one from an ine^pen^ve meter and our 
special pick-up line described by WIJJL in the September 
'65 73< The line with holes drilled is only SI, or you 
can get it with parts atready mounted for $3.50. 

Want a good keyer? We've got boards for two: WA6TSA's 

Uni-Junction Keyer In the January '66 73 can be built 
on our fiber glass board with ihe holes drilled and parts 
locations shown for $4,95. With the transistors mounted 
on it, it's $8.95, 

Another good keyer is WB6AIG's Kindly Keyer in the 
Tuly '66 73. The fiber glass board for this keyer^ with 
all those 120 Uny holes drilled is only $4,95. 
K3LCV's FET Voltmeter is very useful. It*s d^crihed 
in the July *66 73 and a fiber glass board for it is 
$3.50. See the Silicon ix ad in SepUmher for the FET's at 
a fantastic price. 

COMING SOON: WATCH 73 FOR THESE 

PROJECTS! 

Novice receiver and tronsmitter. VHF and UHF dip- 
meters. One wott six meter tronsceiver. Copacitor- 
resistor checker. Portable FM monitor. Wovemeters. 
Calibrators. 

Prfces Include pestaga in U<S.A. Connecticut residents include 
sales tax. kU boards in stock for immediate delivery. 



Harris Company 



56 E. Main Street 



Tarrjngtoiip Conn, 06790 



Gravitation Error 

Dear "3: 

Dwftytie Hendricks WASDZP, of Tek-Dayme Research, 
has sent me a letter about a typographical error in a 
letter to you published m the May issue of 73 about 
^airitation* The volujne of the gravitation was given ai* 
6.3 3t 10'*^ cm^ It should be 6.3 x 10"*= cm*. These values 
were obtained from Nuclear Dynamics by Dr. Nicholas J* 
MedvedefT, one of the leading physicists in the U*S*A* 

Tom Appleby W3AX 

Prefliflcnt 

Mahlon Loomis Scientific Foytidatioti 



The FET Voltmeter Is Great 

Dear 73: 

I am really surprised at the way 73 magazine has passed 
up the other two major ham magazixies, 1 buy a bam 
magazine because 1 want to learn more about solid state 
circuits and 73 has more information about this than any 
other magazine* I have built the Field Effect Voltmeter 
(|uly, J 966 page '34) and Richard Palace, KSLCU, is 
rigtit, I have put aside my high -class test eciuipment for 
this low-cost unit that makes others look sick. As you 
know, it doesn't run from 110 Vac so you can take it with 
you in the field* Keep up the fine work and articles on 
solid state circuits* Thanx for a good magazine. 

Tom Adams, V^ABKSS 
Monrovia, CaliC. 



Ham Use of Semiconductors 

Di-ar Fault 

I fead with great interest (and ftdminaling conccni) 
your comments in the July issue regarding the apparent 
inability of the *'Handb<»ok'' to keep up with the current 
state of the art so far as semi-conductor technology is 
tonc**rned. I have felt for quite a few years now that 
electronics is outrunning the ** bible", but you are tbe first 
I have riui across to state it in print. My congratulations. 

The broadcast industry is one of the most eonserv^ative 
cancenung adoption of neiw electronic techniques. After 
cveryliody else makes all the mistakes, broadcasting will 
step in and utilize equipment that has had all the bugs 
ironed uul. Yet almosit all new broadcast equipment bought 
1)1 built today is 100% solid state* Transmitters are avail- 
able for no more than 20% greater cost over tube models 
up to 5000 watts that are all tranisistor except for the final. 
The two primary reasons for retaining tubes in finals are 
cost and susceptability to lightning damage. 

For a business that bases its entire operation on the 
snccessftd, economical operation of reliable electronic 
equipment with a minimum of man-hours (these men 
have other things to do) sp«mt on upkeep, indifference to 
the advance of the state of the art would be technical 
suicide. 

1 would feel the same thing might appl>' to liam radio^ 
Have not we been famous as technical innovators? Hasn't 
it been our reputation as the hobby hits who "play** with 
electronic in^entions to l^e the first to come forward with 
the x>>'*^t;tical systems? Maybe I'm an alarmiiit, but I fetO 
that hams have been in the forefront of electronic engi- 
ntn^ing until just recently, but now we seem to be falling 
behind. I don't know a radio amateur worthy of being 
called one who can't tell you what happens inside a 
vacuum tube^ but I know very few who can say what 
happens inside a transistor coherently. All that comes out 
is some fogg>' reference to the movement of "holes** or 
some bland statement that ''they work just like tubes, ex- 
cept you reverse the B plus and lower the voltage/* Con- 
cepts bice these are what perpetuate the general feeling 
among hams that transistors are unreliable., hut interesting 
little novelties* Nothing is farther from the truth. Used 
wjirectly they are the most reliable and interesting active 
electronic component available to its today^ It is about 
tinie the hobby as a vvhole accepted this and got on the 
bandwagon. This means the Handbook needs to be bigger 
• , , lots bigger. Maybe this will cost more, but it would be 
worth it» Send the editors back to school if necessary. It 
seems a sad criticism that there were more technically 
valuable semi-conductor articles in the July issue of 73 
than in the entire 1965 Handbook. 'Nuff said? 

Steve Broomeil W0PGN/7, Chief Engineer 
RAH, Casper, Wyoming 



92 



71 MAGAZINE 



Get Your Extra Class License 

Dear 70: 

My article on the esdra class exam and prograjnrDed 
texts appeared in the July 1966 bsue of 73- I have had 
tremendous response to this article, and I have received at 
least a letter per day since that issue came out. Boy, 73 
articles really get the coverage! 

Here's some additional informatiDti I've been giving to 
those hams who responded to my article. Fixst of aU, the 
samplQ pro gram tned lessoas of Fig, 2 in the article didn't 
come from any published text. 1 wrote tliese myself espe- 
cially for the aiticle. Maybe I should write a programmed 
book. 

Second, since 1 wrote the article there have been several 
more programmed texts published. I've listed these below. 
There is a pretty wide selection available now and most 
hams shouldn't have too much trouble tn finding one to 
suit them* Also^ new programmed texts are coming out 
every month or so, so keep in touch with your local boot- 
store. 

Eecent Frogrammed Text-9 
*'A Frogrammed Course in Basic Electronics", New York 
Institute of Technology Series, McGraw-Hill Book Com- 
pany publisher. 
"Electronic Troubleshooting'*, Pliilco Technical Institute, 

Prentice^Hall Inc., Publisher* 
"Logical Electronic Troubleshocrting", by Donald Schuster, 

McGraw-HiU Book Company, Publisher, 
'^Electron Tubes at Work", by J. B. Ovtens and Paul San- 
bom, Tutor-Text^ Doiibleday. 
"Fundament a Ls of Transistors ( Programmed), KCA Service 

Company, Prentice-Halt Inc., Publishen 
'DC Circuit Principles", 

"Simplified Transistor Tht*ory*\ hoth by Training Systems 
Inc., and Stanley Lcvinc, llayden Book Company Inc, 
Publisher. 

I am pleased that my article has been so helpful, and 
tlianks to 73, tt was published. 

Louis E. Frenzel, Jr., W5TOM 
Iloustoii, Texas 

AM on 20? Bah. 

Dear 73: 

There are a couple of items having to do with frequency 
allocation and usage in the 20 -meter band which have 
been bothering me for quite some time. Although both 
subjects have been brought up in the past, I think the time 
is right for further discussion in a national' magazine* 

First, I feel ihnt the frequencies between 14-150 and 
14-200 MHz are a "vast wastland/* i.e., they are receiving 
much less use than tlie rest of 20 meters. From my vantage 
point on the West Coast, it appears that the only use of 
this band segment ist 1. Some AM (and a few SSB) sta- 
tions from VE-Iand; 2. An occasional DX station trans- 
mitting around 14.190 to 14.199; and 3. An occasional 
phone patch from KR6, etc* 1 maintain that all three of 
these uses are absolutely nonessential and this band seg- 
ment would he put to miich better use in this country if 
it were oi?en to U*S* phcuie stations. If the FCC goes ahead 
with incentive licensing, perhaps part or all of this segment 
could l>e used by amateur extra licensees only; othersvise, 
why not open it to all holders of conditional class or higher? 

The second suhj(x*t concerns what IVe been hearing 
lately between 14.200 and 14.250 MHz— that portion of 
(he band set aside by "gentlemen's agreement'* as the sole 
province of AM phone stations* Recently this band segment 
has been more and more populated with SSB stations; 
furthermore, many DX stations have been working U*S. 
SSB stations here. This is a logical development in view 
of the number of amateurs wth transceivers who cannot 
send and receive on different frequencies* 

I propose a new gen tl emends agreement: An agreement 
by AM stations to refrain from transmitting on 20 meters. 
This shouldn't be much of an incon%"enience for anyone, 
since there seems to be less AM acti\ity on this band as 
time goes by* Those who choose to work AM as a matter 
of personal preference can do so on other hands (with less 
interference from "side-winders'*)* Certainly there remains 
no argument on the relative merits of SSB versus AM for 
long haul work. Need 1 say more? 

I hope that my ideas %vill be of interest to other active 
amateurs; I am sure that their implementation would be 
of great value to our important 20-nieter phone band. 

Gerry WA5FRL/WB6PHU 
Facilie Grove, CaJ. 



EVERY HAM i 
SHOULD HAVE ONE! 




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An excellent item for owners of Turner's 
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OCTOBER 1966 



93 




• Great Circle Besfinss • "Q" and "Z" Stenals 

• Great Circle Charts • World Time Chart 

• Prefixes by Countries • tnt'L Postal Rates 

United States Listings.. .$5.00 

DX Listings 3.25 

See your favorite dealer or order direct (add 25( formailins) 



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RADIO AMATEURS REFERENCE LIBRARY 
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An OT Looks at Code 

Dcsir 73: 

For 35 years I hnve felt that it was right and proper 
that every amateur should learn the code for a licciLse. 1 
went through it, why not everj'one else? Hecently I have 
changed my inindl 

1 have been helping a couple of Novices improve theit 
code, One is 79 years old, the other a brilliant young en- 
gineer. Bath of these fellows are in the last months of 
their Novice licenses, and, although they are on the verge 
of passing the code, neither can quite make the grade* The 
old gent win never be ahle to write 13 wptn with a 
pencil. His old fingers y^sX won^t go that fast. His Novice 
license is a means of something to do. He lives out in the 
desert hy himself, and will now have to give up. The 
young engineer understands all there is to know about 
electronics and designs our defense systems. At home he 
copys 20 wpm but blows up at the radio inspectors office. 
Every month for five months he has plunked down S4-0n 
to take the test and missed by one letter. He never ex* 
pects to use CW, in fact he hates it, but likes SSB and 
construction. The old gent is hard of hearing, CW corner 
through where SSB does not. There must be a moral 

Have we been wrong? Why can't the Novice stay on 
forever if he likes CW at 5 wpm? Who is he harming? 
How many Novices can pass 13 wpm at the end of the 
year? I have not found one with w^hom I have been in 
contact? How many phone men could pass the code if 
the Rl came around? 

Tlie e:ccuse for CW was to* provide CW operfltors for 
the militar>% Do we still need CW operators w^hen the 
infantry^ soldier has digital communication back packs? 

Since our license method is so screwed up, why not 
leave the Novice alone for a few years until he CAN 
copy better and give him a decent chance. 

What was wrong with the old test 30 years ago: 10 
wpm (a reasonable speed) and some theory? Whose ego 
arc we trying to please by the complexity? A few who 
want special privileges because the bands are so crowded. 
At one moment we holler for more amateurs and the next 
for Esrtra class licenses. With the few Extra class licenses 
issued, I doubt if they will make any impact on increasing 
our engineering abilitj' to save the electronic industry. 
Engineers are made in colleges. We are hams. Why not 
leave us alone? 

I say let's have one reasonable license and a cont i minus 
Novice if we must, hut lePs do mtnethin^ and get this 
mess stTflightcned out. It's been hanging fire too many 
years* 

Ed Marriner, WfiRLZ 
La Jollu> Ciilifurnia 

P.S. I have the Extra class amateur besides commercial 
first telegraph and phone licenses. 



Green, No, Articles, Yes. 

Dear Sirs; 

I do not m the least agree with your Mr* Green; in 
fact I think he is a rabble rouser. 

However 1 must admit tiiat 73 is printing some ver>^ 
good articles. So please enter my subscription for one 
year and 111 enjoy the magazine and try to ignore 
Mr, Green, 

Eugene Bulton W6FVE 
Modesto y California 

On Wayne Green 

Bear 73: 

So you wonder what sort of a guy he is? Is he a crabby 
basket^ an angry old man or an impatient young man 
irith ulcers or what? 

I confess I waited at the Air Fort in Nairobi with 
mixed feelings. 1 had had several Q.S.O.'s with him and 
found him quite pleasant but his editorials!! 

He mustt as a successful aut!ior and editor of many 
years, surely be at least fifty or sixty. I had a hearty 
respect for his views and his editorials but some of them 
were Vitriolic and his debunking was at times merciless. 

He would of course wear a tired lined old face showing 
the strain, on the other hand he was looking forward to 
skin diving in our lagoons, it didn't quite match up. 

First Larry and ]tm arrived and then a pleasant looking 
young man of about forty came through the barrier with 



94 



73 MAGAZINS 



a wide grin across his face, ''Hello Robby, nice to meet 
you" I was holding up a C,Q, and a Q.S.T. magazme for 
hii» to identify me in the crowd. He took the joke very 
weU and we had a good laugh. My qualms vaiahed— for 
good. He is most eatertaining to talk to and is interested 
in everything qb this little earth and beyond including 
an inquisitive mind an flying saucers] A vast fund of 
general knowledge, an open mind (most sufprising of all) 
and has a youthful burning enthusiasm for some of liis 
hobbies of the moment combined with the maturity of well 
balanced views and opinions. 

You have to be wide awake when he embarks on red 
hot topics such as the possibilities of us losing more ham 
bands* He feels far too many of us don't realize how 
easily we could be voted off all the bands by fragmented 
Africa, each separate little country with a voting power 
the same as U.S.A. and U.K. In fact Vm quite worried 
about it now but its a comfort to hope that the Crusaders 
like Wa>'ne wiU save some of it, somehow, I hope! 

About his editorials, I feel he has an impish sense of 
humour behind it all and perhaps a curiosity to see what 
would happen or how people would react! So when he 
writes his outbursts he keeps his tongue in his cheek. 
That's my opinion only of course but one day of safari is 
like a month on a ship or years of acquaintance, 

I had a shock coming when I turned him loose in the 
shack. His left hand got cold, in fact it froze solid, on 
the microphone and he couldnH let go until 2:30 a.m, 

H© made his stateside contact and got his home mes- 
sages off and said *'Mind if 1 give a few boys a 5Z4?" 
He then started working three a minute with occasional 
short QSO's with special pals. It might surprise you but 
Wayne is an accomplished operator he was finishing off my 
log book when I went to bed and next moring I found 
a neat pile of foolscap paper closelined with 48 contacts 

per page!! 

I didn't count up the contacts but they were quite a 
few hundred and for stretches ran three to the minute* 
He controls the crowd well and is a cool operator. T asked 
him why he ticked off one lid and left another alone, in 
fact went out of his way for him. It turned out thai by 
die call sign the guy was pretty new whereas the other 
one was an old prefix **who should know by now how to 
operate/' 

He had that impish grin on again and was obviously 
wondering how the guy would react. The guy reacted ok 
and Wayne soothed him with a kind word and settled 
down again to three a minute. 

Ok, so what, 1 know a few other guys who can do that 
but they axe not Editors! Wayne does all his hobbies well 
and goes flat out. 

WTien on safari we drove up to a fine herd of Elephant 
and Wayne was filming away. Suddenly a second herd 
appeared behind, us. We couldn^t go backwards or forward 
as we were on a swamp path. The second herd wanted 
to join the first herd and we were in the way and awfully 
close to them. WajTie just said "the first group is the 
better** and went on filming them. He*s cool, outwardly 

an>Ti'ayI 

I usually get fun telling visitors "try again with the 
lens cap off" and so on, but Wayne used his movie and 
three cameras and a Polaroid in quick succession without 
any flufiing. He keeps them as preset as possible, that is, 
ready to shoot which is a great help to me as I found I 
could take him right vip to a beast— and in an incredil>ly 
short space of time he had the shots he wanted and said 
**ok" and we slipped off before tlie animal could decide 
what to do about it. 

The Masai guide spoke in English but occasionally 
spoke in Swahih for my benefit and said "Bwana Hapana 
Mbia" which literally means '*The man isn*t bad'* which 
h high praise from a Masai warrior. It means of course 
that Wa\Tfie perfonned well If he hadn't the Masai would 
have sniffed, spat out o( the window and clammed upt 

I hope Wa>Tie will tell you of Ms great travel saga-it 
u^ill l>e interesting if he does I promise you. 

So there it is* a delightfuT companion, an alarmingly 
high I.Q,, very thoughtful, hardly drinks, good fun and 
game for anything, 

I must get this letter off to *'73'* magazine and see if 
they'll print it quick before Wayne gets l>ack! 

Bv the way— he eats too much! 

Robliy Bobson BZ4E^1\ 
Nairobi, Kenya 
August II, 1966 




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We started quizzing the Alitalia people care- 
fully to find out why our flight had been can- 
celled and when. The story we got was that 
it had been cancelled at least a day eariler . * . 
well before we had even left Boston. Why was 
it cancelled? Well, they explained that due to 
the U.S. ail line siiike there was a lot of money 
to be made in transatlantic flights and tliat the 
plane had been put on that run since it would 
bring more profit, I don*t know how lATA 
feels about this sort of tiling, but Til bet the 
FA A would raise hell with an American line 
that pulled this. 

That night we had dinner in A then s^ hotel 
and food courtesy Alitalia. This was nice, but 
we were losing over $100 a day on our safari. 
The next morning we did the Acropolis and 
snapped beaucoup pictures. We did OK in 
Athens, only losing three cartons of cigarettes 
to the taxi driver that took us to the Hotel 
room (Hotel Eiektra), It could have been 
much worse. 

The flight to Nairobi left about 1 am the 
next morning (Friday) and stopped for an hour 
at Cairo at 3 am. Postcards were 25^ each so 
we looked bul did not buv. Next Asmara in 
Ethiopia for another stop. Then on to Addis 
Ababa %\here we stopped for an hour and a 
half wliile Africans crawled all over the plane 



96 



71 MAGAZINE 





cleaning it It was an Ethiopian Airline plane, 
so this was reasonable. Every flight was 
jammed solid and there was no possibility of 
sleeping in the crowded tourist section. We 
were rubbing elbows with men in white sheets, 
colorfully robed Africans and a good many 
Indians. 

We set down in Nairobi at noon and, the 
customs formalities done, found Robby wait- 
ing for us. He identified himself by holding up 
a copy of QST and CQ. Bless him. Shamsu 
Din, the fellow who booked our safari, was 
also waiting for us. We drove about four miles 
into town and had a short lunch under the 
big thorn tree in front of the New Stanley 
Hotel At th§ next table, I saw with dismay, 
was a long haired boy in tight dungarees and 
a black leather jacket. Good giief! He was 
with a group of boys and girls that could have 
been transplanted from Peterborough, New 
York or Stockholm. 

The afternoon was taken with getting our 
hunting licenses, selecting our guns and regis- 
tering them. Groggy almost to the point of in- 
coherency we sacked out at Robby 's house for 
the night. The next morning (Saturday) we 
admired his formidable barrage of antennas 
and nice station, I wish we*d had time to get 
on the air for a httle bit, but we had to get 
downtown for a little shopping before driving 
to Nanyuki some 125 miles north for our sa- 
fari. We bought safari shges, safari jackets and 
safari hats and walked with fust a touch of 
swagger dovm, the main street of Nairobi, After 
stocking up on film we piled into Shamsu*s car 
and were on our way. The car had a king pin 
about to give away plus two front wheel bear- 
ings burnt out so we didn't make very good 
time. We skipped lunch and drove straight 
through, stopping only for a half hour in 
Thika to have one of the wheel bearings re- 
placed. We arrived in Nanyuki at about four 
in the afternoon, 

Nanyuki is a very small town right next to 
the highest mountain in Kenya, Mount Kenya 
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equator, but because it is about 6000 feet ele- 
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of stores run by Africans. One that sticks in 
mind was the Butchery and Tea Room, an in- 
teresting combination, Shamsu suggested that 
we shop in the Indian shops as we might get 
into trouble in the other part of town, Hmmm, 

The Sportsman's Arms Hotel turned out to 
be a pleasant place . . . rather mn down by 
American standards. Old battered furniture, 
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OCTOBER 1966 



97 










Wayne on ternnite 



made up of 30 or so rooms in a motel arrange- 
ment - - , some all in a line, some separate 
cabins. My room had two single sized beds, a 
clothes closet and an old dresser. There were 
two beat up chairs. The bathroom had an old 
tub and a waslistand* In a small separate cu- 
bical was the toilet. The lighting was from a 
hanging overhead bulb. Meals tmned out to be 
large with six to seven courses, though the 
preparation \\ as not inspired. 

Relatively few of the Africans speak much 
English and you start riglit out getting a basic 
vocabulary of Swahili. You can get along 
pretty well with as little as fifty words and 
with 500 you are fluent. 

Soon after we had had some sandwiches to 
make up for our missed kmch Fred Seed^ our 
White Hunter, arrived. We set out immedi- 
ately to zero our rifles and get used to them. 
We drove about two miles out of town to a 
rifle range and proceeded to see what we could 
do with a 100 yard target. One rifle turned 
out to be defective and it was nearly impos- 
sible to extract the used slielL The otlier 
worked OK, but was way out of adjustment 
and it took about 14 rounds to get it on tar- 
get. Those shells cost over 50^ each so we 
iked sparingly. Oh well, only one of us can 
shoot at one time anvway . . - and only 
Larry and I will be doing the hunting. Jim 
decided to devote his time to filming. 

On Sunday morning we all drov^e out to 
the range again to make sure we had tlie *338 
on target . ♦ , seemed OK. Then we were off 
on the iiunt. I was up first so I sat by the door 
of the Land Rover with Larry in the middle 
and Fred driving on the right hand side. In 
the back seat were our two gun bearers, 
watching out tlie sides for game, and Jim in 
the middle, popping up di rough the hatch in 
the roof to take pictures. In the very back of 
the car was the skimier, just in case we man- 
aged not to miss something. 



The countryside was grassy - . . sort of a 
crab-grass stuff • . . with acacia (aa-case- 
eeya) tliorn trees everywhere). These spindly 
trees grow about ten feet apart, are covered 
with exti^emely sharp thorns and are swarming 
with ants. The ants bite into the bark, causing 
it to swell up into blisters an inch or so in 
diameter J where the ants live. These are called 
wliistling thorns because the wind blowing by 
these millions of blisters makes them whistle 
and you hear this eerie whistling sound when 
the wdnd blows. 

We drove a couple more miles and were 
definitely in the bush. We began to see signs 
of animal life with little herds of Thomson's 
Gazelles running around. Fred pulled to a stop 
and pointed out a large Tommy ram and said 
to go after it, Kerede, my bearer, handed me 
the gim and I tried to load it. Tlie shell re- 
fused to go into the chamber, I poked the 
shells in the magazine to get them to pop up 
and threw the bolt again only to have two 
shells try to jam in» I took them out and 
feverishly put them back in the magazine and 
tried to load again. No good. After about a 
minute of this ridiculousness I finally got a 
shell in the gun and the gun on safe. By then 
the ToDimys were off in the woods out of sight. 
Kerede took the gun and we started off, I 
walked as carefully as I could, trying not to 
make any noise. Kerede crouched along, vdth 
me bent over trying to keep up with him, 
breathing liarder and harder at the unusual 
position and suffering a bit from the thin air 
at this altitude. It was hot and sunny, 
about 75''. 

We tracked them for about ten minutes and 
then Kerede motioned that they were spooked 
and we returned to the car. We drove for an- 
other mile and spotted another group of 
Tommys and we were off again. Same result. 

Then, as we came out onto an open field I 
saw a lone Tommy ram grazing, I looked 
through my binoculars and he looked like a 
good trophy- Nearby I spotted a small grey 
dog sneaking up on the Tommy . * * it was 
a jackah I jumped out of the car, took tlie 
gun and got in the clear and aimed as care- 
fully as I could. A Tommy is about three feet 
high and not a large target. This one was a 
tiny tan spot in my scope wavering back and 
forth across the cross-hairs. I squeezed the 
trigger and watched for the puff of dirt and 
running Tommy* Instead the Tonmiy did a 
little flip and dropped. I was astounded* I re- 
loaded in case he jumped up again wounded 
and ran across the field to him. He was about 
200 yards away and I was well winded when I 
arrived. The shot had caught him in the back 
and killed him almost instantly. Not bad for 



73 MAGAZINI 




that distance. 

It seems a shame to kill these beautiful Kttle 
antelopes J but they are a pest to tlie farmers 
and cattlemen of the area and they want them 
killed. The whole area around Nanyuki is made 
up of large ranches and farms* Cattle raising 
is the big business here and most of the conn- 
try is divided up into blocks of about 1000 
acres which are fenced off to keep the cattle 
from straying. The antelope eat the grass, 
which is not all too plentiful TheyVe had 
little rain in the last two years and it takes 
about 50 acres to feed one steer. 

One of the ranches (15,000 acres) recently 
sold for $90,0003 to give you an idea of land 
values. The rancher must continue to improve 
his land or else the government steps in and 
takes it away from him^ pa\'ing him their ap- 
praisal, and di\ ides it up among Africans- The 
ranches still have a good deal of wild game on 
them and it is mostly a headache. Giraffes and 
zebras break the fences . * . antelope eat the 
grass, etc. The owner can go out and extermi- 
nate the game, but he must turn the carcasses 
over to the wild life department. He cannot 
use the meat or skins or sell any part of it. He 
gets a Httle help from hunters, but they are 
limited in the number of animals they can 
shoot by their licenses. My license permits me 
to shoot and eland and an oryx. I could have 
two impala, two waterbuck^ three zebra^ and 
a few other things, I bought a special license 
to shoot an eland and an oryx. I could have 
bought a license for elephant, rhino, etc, but 
I would have had to rent a larger gun and 
pay stiff license fees for this. Perhaps some 
other trip. ^ ^I 

Larry was now in the shooting seat. Before 
long we saw a small herd of Tommys and he 
and his bearer Labun went out after a ram. 
We heard the shot after a few^ minutes and 
drove over and picked up the dead Tommy- A 
nice one , , • meat on the table for us and a 
nice skin for Larry* 

My turn. We caught a glimpse of some im- 
pala, Kerede and I went after them. Kerede 
stopped and pointed • • . I aimed the gun 
and looked through the gun scope* All I could 
see w^as the rear end of an impala • . . I 
couldn't even tell if it was a buck. I went back 
to the car and got my binoculars and took a 
closer look. It looked hke a lousy shot Larry 
said he'd like to try it and he took a shot- 
Notlung. 

We lunched in the shade of a larger thorn 
tree, washing chicken sandwiches dowTi with 
warm Pepsi . . _ tasted good at the time. A 
whole pineapple for dessert. OK, back to the 
hunting. 

After a little driving around we came across 



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the impala herd again and I stalked them for 
a bit and saw that I wasn't going to get much 
closer so I steadied do^vn as best I could and 
pinged- Miss. Damn. 

It was late afternoon before we had another 
chance* I glimpsed a Grants gazelle off in the 
woods and Larry went after him. He blasted 
and the Grant took off. I could see he was hit 
and in trouble with my glasses. Larry and La- 
bun went after him and Freddy, Kerede and I 
followed at a distance. We lost them. After 
about a mile we heard a shot and headed in 
that direction. Larry had finished him oft . , , 
a very good specimen. Freddy went back and 
drove tlie car in to pick up iis and the Grant. 

It was quite a day. We had dinner at the 
hotel at 7:30 and went right to bed dead tired. 

The next morning, our second day of hunt- 
ing, I started the day off right by missing an 
impnla buck. Larr)^ got a chance at one a 
little later and again had to follow to finish 
him off. Bad luck. It was a fine old buck 
though with a nice rack We went back to the 
hotel for lunch this time, being just about five 
miles out of town. We set out again at 4:30, 
when the heat of the day had cooled a bit 
and the animals would be on the move again, 
\Ve were looking for impala so naturally every* 
where we went we found Tommys. Late in the 
afternoon we saw some impala about 300 yards 
away, I got out and got up to about 250 yards 
when I spotted a tremendous buck. He was 
magnificent, I could see that he was about to 
spook so I steadied my gun on a fence post 
and took careful aim . . , just as I went to 
shoot he turned and left. Labun and I went 
after him for about a mile and I never had 
much of a shot at him- Finally^ I popped one 
off in desperation at over 200 yards, but it was 
an ob\ious miss. 

We drove into another ranch and some 
more impala turned up, Larry went with La- 
bun after them and soon we heard a shot, I 
grabbed my telephoto camera and followed, I 
came upon them about 100 yards in the woods 
and Freddy gave me the gun and pointed to 
the impala herd still standing about 200 yards 
away, Labun went widi me and soon I took 
aim at the buck he pointed out. He went dow^n 
immediately and we found that my shot had 
hit him right in the heart. He was about 100 
yards away. He didn't have as nice a rack as 
the one Larry shot so I decided to keep his 
skin, which was gorgeous. We also took the 
meat back to have for dinner. It was delicious. 

The next morning I tried again for that big 
impala and failed to get near enough. Later 
on we were driving through some rather open 
woods when a nice group of impala spooked, 
ICerede and I followed them and as we were 



IW 



7Z MAGAZINE 




closing in there on my It f I was a huge animal 
1 didn't have any idea what it was. At first I 
thought it was a Brahma biill, but the horns 
were wrong • . , and Kerede was telling me 
to shoot it I aimed carefully and plonked him 
in the shoulder. He keeled over immediately, 
to my amazement. It vvasn^t until after the 
picture taking and excitement w^ere over that 
I learned that I had polislied off a near record 
waterbuck. He \vas too big to load in the car 
so they chopped him m half. 

This was such a big Irophy that it put a 
damper on the shooting and we spent tlie rest 
of the day sightseeing and taking pictures. We 
saw lots of ostriches, pelicans, secretar>^ birds, 
and even giraffes- 

The next day we drove out in a different di* 
rection and drove about 150 miles sightseeing. 
The country was fabulous and w^e saw 
baboons, lots of Tommys, Grants, impala, dik 
dik and even a small herd of eland. I was still 
off shooting so we )ust looked and clicked. We 
met a rancher there* a wonderfully interesting 
man, married to an African wife. He was fust 
coming back from checking his herd of sheep- 
He has to sleep with the herd every night to 
keep Africans from stealing them, I wondered 
why he didn*t hire a herder (government stand- 
ard wage for herders is $20 a month plus 
food), but found that herders are OK for pro- 
tecting the sheep against normal problems, but 
when rustlers show up they frequendy strike 
a bargain with them and off go a bunch of 
sheep. So Jack sleeps with liis sheep. 

So far we had been hunting entirely on 
private lands. You have to reserve public lands 
considerably ahead of time if you want to hunt 
them and, despite his promises to do so, 
Shanisu hadn't reserved any hunting blocks for 
us. Fortunatelv Freddv had a good friend 
hunting in nearby 13lock 67 and he got per- 
mission for us to go in there and pop a zebra 
or oryx, Thursday morning we started out for 
67. It was about a 40-mile drive to the check- 
in gate . - , then a few more miles to a little 
\illage of Ndorodor where we stopped and 
bought some candy and cigarettes to trade 
for photographs of natives. A local entrepre- 
neur who called himself Lamumba took charge 
and got several of the local girls lined up for 
photographs, standing benignly behind them 
with his fly whisk. He could speak enough 
English to get by and we shelled out a shilling 
{\\^) each to the girls and a Polaroid photo 
for him. He wanted a dollar too, but we 
shoved off* 

W'e were in Masai country now and every 
now and then we would pass one with a spear 
in hand, paint on his face, and interesting 
things hanging from his stretched earlobes. 




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One had a Kodak 35nim film can and was very 
proud of it- 
Then we came to the escarpment. Here the 
plains at 6000 feet dropped off suddenly to 
about 3000 feet. The road wound itself down 
the face and it got hotter and hotter. This was 
more like the equator. We got to die bottom 
and found ourselves in very warm desert coun- 
try. There were some fellows working on the 
road \\ith Caterpillar tractors. One of them 
thumbed a ride with us about a mile from the 
bottom of the escarpment to a thorn enclosed 
camp about a mile away where police were 
staying. It seems there is a small war going 
on in northern Kenya. The Shifta, a nomadic 
tribe of about 250,000 living on the border of 
Somalia, didn't mind being ruled by the Brit- 
ish, but object strenuously to being ruled by 
tlie Kenya government. The result is that they 
have been fighting a guerrilla w^ar for the last 
two years » Apparently tlie communists have 
been supporting them and the fight has ex- 
panded well down into tlie northern frontier 
of Kenya, 

We drove thiough the desert^ seeing little 
animal life. There \\v\q huge mounds of ele- 
phant droppings, but at this time of day they 
were off in the surrounding hills to keep cooL 
A herd of oryx spooked as we came around a 
corner. 1 went off after them with Kerede and 
Freddy^ but after fifteen minutes we saw it 
would be a long back and turned back. We 
had a nice lunch on tlic bank of the Kipsing 
river. The river was about ten inches wide with 
a drv'wash of about 50 feet or so. There were 
footprints from elephant, rhino and fust about 
everything else imaginable. 

It was getting late in the afternoon so w^e 
headed back. The trip up the escarpment was 
a dilly. The Land Rover had to go in its lowest 
gear with all four wheels engaged to make it 
in many places. Little else could possibly get 
up there. As we went through Ndorodor again 
Lamumba flagged us down and asked us to 
take him and his wife to Naii\'Tiki, No. But his 
cliild is sick and must get to tlie hospital. OK, 
well take them to the hospital, but no place 
else. So he loaded Ins wffe and two children 
in the back of the car and jammed liimself in 
the back seat beside Jim, whisking him a few 
times with his fly whisk. He smelled pretty 
boozy, among other things. When we arrived 
in Nanyuki he lost his command of English 
and Swahili and could understand nothing we 
said. He did commmiicate tliat he wanted to 
get off at the Butcher and Tea Room, the local 
diinking place. We obliged and Freddy again 
vowed never to give another ride to anyone, 
no matter what. 

We learried the next morning that the Shifta 



102 



73 MAGAZINE 





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OCTOBER 1966 



103 



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had iitruck at the foot of the escarpment, right 
where we had been^ about an hour after our 
passing and six men were killed and three 
wounded. That was a close call. 

By Friday our bloodthirst was back and w^e 
set out for more hunting. I started the day out 
right by walloping a nice impala. It was a very 
good shot and, when we took him apart, found 
that the bullet had exploded his heart. Even 
so he made it about fifty yards before dropping 
and I was afraid I had just wounded him. The 
shot was about 100 yards, I have to admit that 
1 muffed an impala earlier though- I thought 
I was dead on him and the bullet whacked as 
if it was a hit. The impala just stood tliere so 
I was sure it was a hit and he would fall down 
or else I would have shot him again immedi- 
ately. Then he wandered off and I pinged 
another after Mm, missing again. There was 
a nice hole in the tiee just behind him, the 
whack we heard. You can usually tell, even 
from quite far off^ if a shot is a hit. 

Baron Von Scheken^ one of the most pro- 
gressive farmers and ranchers in this area, was 
most anxious to have us bop some of the zebra 
that are breaking his fences so he drove out 
with us in his Rover to show us where the 
herd was at the moment. Larry and Labun 
took off on a long stalk with Freddy backing 
him up in case of a wounded animaL They 
must have been gone almost two hours before 
the shot came. No whacky so it was a miss. 
They came back to the car and we headed off 
to try to find them again. Suddenly we came 
on a herd of waterbuck. It was mv turn to 
shoot, but I had my waterbuck so Larry got 
out again and went with Labun into the woods 
to circle them and come in downwind. We 
drove off to allay suspicion. About twenty min* 
utes later came the bang and whack* Good* 
We drove back but couldn't find either of them. 
About fifteen minutes later they came in view. 
It seems that Labun had followed the wrong 
waterbuck and the one Larry hit was just 
about 50 yards from where he had killed it, 
behind a bush. We took pictures in the failing 
light. It w^as a fine waterbuck. The Baron was 
pleased. 

On Saturday (today) Larry went out alone 
while I stayed at the hotel pecking out this 
brief report. He came back about ten in the 
morning to announce that he had knocked over 
two of his three zebras already, I sure hope 
that rU get one or two tomorrow when I get 
out there. 

The hunting is enjoyable , . . the weather 
here is excellent We need every one of those 
four blankets at night even though we are on 
the equator. We'll hunt another week here 
and then pop on back to Nairobi for a few 
days J probably visiting the game preserve there 



104 



73 MAGAZINE 





with Robby and then driving down to see the 
Lake Amboselli game preserve. From there we 
plan to visit Murchison Falls in Uganda, with 
a stop at 5Z4JW on the way. Then, if things 
are calm in the Congo, we will drive over and 
visit 9Q5HF and 9Q5IA and back into Rwanda 
to 9X5GG, If things are touchy there we may 
come back enrh'er and go on our wav to El\ 
ST, SU, OD, etc. 

The time was when a hunting safari to 
Kenya was a very expensive deal, possible only 
to the ver}' wealthy. It entailed dozens of men 
to carry the tents, food, gims, and equipment 
and weeks in the jungles fighting off heat, 
bugs, and dysenter>% 111 tell you exactly what 
tliis whole works cost when I get all done, but 
right now the basic expenses have been $690 
for the three weeks in the hotel plus all hunt- 
ing costs, though we cut down on this a bit 
by splitting the total cost for two hunters and 
one non*hunter ($345), coming out to about 
$575 each for the three weeks. The gun cost 
$90^ including the license and 140 rounds of 
ammTinition, The hmiting license cost me 
$120, though I could have just as well bought 
the $57 license if I hadn't inchided the right to 
shoot on public lands and the special orxy and 
eland permits. I figured tliat since I don't get 
to Africa all that often I had better spend the 
extra and be suie. Larry bought the private 
land $57 license and has had no problem. 
They even have cheaper license available if 
you want to just shoot one each of the plains 
game . . . and for only $14 you can go out 
and pop two animals. Something for every 
poeketbook. 

Vll have some expen.se in getting my tro- 
phies prepared and skins tanned and shipped 
3ack to the U.S. And add $100 or so for films 
, , . better make that $200 since 1 shoot first 
and ask questions later. And well have to 
budget perhaps $50 each at most for tips for 
our gun bearers. The whole works is still a 
fantastic bargain. Of course the fly in the oint- 
ment is the air fare over here, which is brutal. 
It is almost tlie same as the around-the-world 
fare , , . it cost me about $200 extra to 
continue from Kenya on around the world 
rather than just flying straight back, 

I was surprised to find out how few^ people 
come to Africa to hunt, I don't know^ what I 
imagined, but last year they sold only 480 
hunting licenses and this year they hope to 
break 300, When you consider that the great 
bulk of the hunting in Africa is taking place 
in Kenya you ean see that fe\v people are in- 
volved yet. For that matter there are only 62 
fully licensed proft^ssional hunters and only 
about 20 of those make a full time job out of 
the profession. Eight <if the hunters live in 



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HW12. 22.32 OWNER 



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I 
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I 
I 
i 
I 
i 
I 



OCTOBER 1966 



105 




^ 



LIBERTY ELECTRONICS WANTS TO BUY FOR CASH 



Electron tubes and 
semiconductors 

Most any type or quantity 

Receiving, transmftting, special 

purpose, magnetfons, klystrons 

We will make you an immediate 

offer in casli. 



Special sale 

HP-200BR audio 
oscillator $65 



Surplus communication and test equipment 

AN/GRC'3, 4, 5, 6, T, 8, 10, 19, 26, 21, 46, VRC-12 

AN/PRC-8, 9, to, 25 

Test equipment with ARM, SG, URM, UPM, USM, and TS prefixes 

Communications: AN/TRG«1, 24, 35, 36 

Receivers: AN/APR-9, 13, 14, R-3B8A, R'2T4, R-390A, R-391, etc. 

Indicators! ID*250, 251, 3ST, 257 A, etc. 

Aircraft: AH/ARC-21, 34, 38, 44, 52, 55, 57, 73, 84 

AH/ARH-14, 59, 67, 70 

ANyAPS-42, 81 

AM/APN-1, AN/CPN-2A 

Also: Tektronix, Hewlett Packard, Booten, and General Radio 

equipment, etc. 



Liberty Electronics^ Inc. 

548 Broadway. New York, New York 10012. Phone 212-925-6000 




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Nanytiki, so you can see that this is a very 
popular game area, 

Kenya has been self- governed for just two 
years so far and it is really going quite well 
considering the enormity of the problems they 
faced. The total population of Kenya is a little 
over 10 million of which about one half mil- 
lion are Asian and 50,000 European (white)- 
Few of the Africans have had much education 
and you might draw a rough parallel if you 
imagined what would happen to our country 
if suddenly it were turned over to seven or 
eight year olds to run. The Africans are just 
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savagery and old patterns of living take a 
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1 find just about everyone here optimistic 
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cessful ones dow^n in Rhodesia and run a sort 
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camping expeditions and plains game hunting 
for those interested right on his ranch to keep 
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and ril bet it would work. If the supersonic 
planes bring down air fares Kenya wdll be 
cro\^^ded with tourists. 

Li.sten for me on 14230. TU be on tliere at 
every opportunity ^ wherever I am, 

. , . W2NSD/1A5Z4 



106 



73 MAGAZtNE 



I 



FIELD-EFFECT 
TRANSISTOR 



WATTS 



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LOW NOISE FETs 



Tube 
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Afnt 



POWER TRANSISTOR 



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similar to 

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2N30Sf) 



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SILICON POWER STUD RECTIFIERS 



FACTORY 
TESTED 



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■ « f «<*«i#J-ftai 



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BIDIRECTIONAL TRANSISTORS, 2NHin .„„ ,*...$1 

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4 2N33 6 NPN SILICON ii-iin^iHtors, Transistron %\ 
10 ZENERS REFERENCES .stud. HSSt tyjies . 
25 GERMANIUM & SILICON DIODES, no test 
25 TOP HAT RECTIFIERS, sjlioon, TfjOma, no test 

10 TOOO MC-1N251 GERMANIUM DiODES — ,, 

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H 60 TUBULAR CONDENSERS, to .5mf, to iKv, ass^t $1 

D 40 DISC CONDENSERS, Zl mmf to ,05 mf to IKV $1 

Z} 60 TUBE SOCKETS, receptacles, pluRs, audio, etc, $1 

H 30 POWER RESISTORS, h to 50W, to 24 K ohmn ,„,Jl 

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R.D, 1 
Freeville, N,Y. 



Zener Diodes 

This excellent article explains how zeners work^ 
how to use them^ how to test them^ and how to buy 
them. Ifs another of TS's technical feature articles. 



One of the many solid-state devices now 
available to the radio anuiteur builder is the 
zener diode. Properly used^ it serves as a ref- 
erence voltage source capable of delivering 
considerable current Unlike a battery, its life 
is indefinitely long, although it must be sup- 
plied with a continuous current for many of 
its applications. This article contains the basic 
inform a tioM rec|uired to intelligently design 
and use zener diodes, and some selected 
sources of information from the ratlier sparse 
supply are listed in a bibliography at the end. 

For instance 

The nmnber one application of zener diodes 
is probably dc voltage regulation for transistor 
circuits. Suppose you have just purchased a 
new 1N2974 zener for about $5T0. The cata- 
log says 10 wattSj 10 volts, 20% tolerance. 
Since you lack experience with zeners^ you 
breadboard the intended circuit to pick up a 
few details on what zener regulators do. Per- 
liaps the circuit is tluit of Fig. 1, Careful! The 
illustrated circuit is more suited to my pur- 



Fig, K A possible hit- 
or*miss zener regula- 
tor circuit. What's 
wrong with 't? 









24V 

400 NIV HUM 
* — 




K 


1 Aiipl\ 

J 


T * 


24VDC 
POWER 
SUPPty 


1 B 


[ a.flv 

1 TOMV MUM 


^^ 


^ 


JOV* zot 
lOm ZtHEH 



poses than yours! You turn it on and this 
might be what happens: 

A voltage measurement reveals regulation at 
8,5 volts rather than the indicated 10 volts. You 
notice the voltage seems to be creeping up as 
you watch the meter, A signal tracer probe on 
point A finds lots of hum; but there is some 
at B too. Perhaps if some current is drawn 
from li the hum will decrease, A load test 
shows little eilect on the hum except that 
under very heavy load the hum increases , • . 
some other noise too! Thinking about that, 
you smell smoke; it's tlie series resistor over- 
heating. As you reach over to turn off the 
power supply, you notice the zener voltage 
seems to have dropped to zero. This reminds 
you that the zener has been operating without 
a heat sink- It's failed completely! Terriblcp 
You can avoid the damage to wallet and peace 
of mind by using the following materia L After 
reading, get out a pencil and some old en- 
velopes or something, and design zener cir- 
cuits. You'll soon catch the idea! 

Zener facts 

Zener diodes are supplied in a large variety 
of packages. The controlling factor is how 
much heat must be dissipated. A majority of 
t!ie zenei-s available are supplied in a diode- 
like glass package for up to 250 milliwatts, a 
wire-mounted cylinder resembling a resistor 
or a silicon rectifier for the 1-watt size, a stud- 
mounting package for the 10-watt size, and a 



loa 



71 MAGAZINE 



inch 






rtaf z«Her 







Z%0 mw 



larger package resembling a power transistor 

for the 50-watt size. ^ ^ 

A catalog search brought out hundreds of |^^*^ I 

zeners rated from 250 milhwatts to 50 watts. ' 

Some engineering books mention zeners as 
small as 50 milliwatts (Cutler) to as large as 
100 watts (Littauer). Operating voltages 
ranged from 3 volts to 200 or so. The least .^^^ 

expensive were priced at 75 cents (General P^^^^J 

Electric Z4XL series). $20 seemed to be the ^^p^ 

upper limit, with a large variety in the $4-$7 
range. Price tends to increase with liighei 
power rating and closer tolerance, but some 
good zeners are available in epoxy packages 
at low prices. 

Some ordinary silicon diodes and transistors 
may be used as zeners.^ General Electric says 1 I Jp 

some of their epoxy cased transistors can be 

used in this way. But most zeners are slightly 1 jf OftO ^ • O d O 

special silicon diodes, designed to dissipate the 
fairly large amounts of lieat produced in nor- 
mal zener operation. Small zeners dissipate the ^ §WlifSf 
heat along theii* leads or into the air; 10 watt 

Fig. 3. Inside the case of a 1 0-watt zener. The ac- 
tual PN junction is in the tiny square ot the center 
of the circle, 

and larger zeners are built like power transis- 
tors. The semiconductor material is brazed to 
a copper stud or surface which provides the 
route for dissipating excess heat into the re- 
quued heat sink. Fig. 2 shows some typical 
zeners. 

Only a small part of the package called a 
zener diode is actually the working element. 
This key piece is a semicoridnctor PN junction 
formed on a silicon wafer by a process in- 
volving some heat and considerable accuracy. 
Fig, 3 shows the interior of a 10 watt zenen 
hi nonnal zener operation the PN junction is 
biased opposite to the direction of easy con- 
duct ion^ at a voltage great enough so it con- 
ducts anyway. Sounds rough, but works fine. 
The arrangement is caUed reverse bias, and 
the zener always appears in the schematic 
witli its arrow pointing toward the positive 
supply line. Fig, 4 is a graph of current plotted 
against voltage for nonnal zener operation. 

A small voltage invokes very little current. 
As the voltages approaches 10 volts, the cur- 
rent increases quite drastically toward some 
terrific value as the zener begins to act like 
a short circuit. If there is no current- limiting 
resistance in the dicuit, the zener w^ill 
promptly perish. This very rapid current upon 
voltage dependence gives the zener its useful 
voltage regulating property. Tiie region of the 











10 twatl" 
10-32 stud 






Fig. 2. Some typical zener diodes. They look just 
like ordinory diodes. Perhaps some of your diodes 
ore zener diodes! 



^See K9VXL*s article, "Save That Tramistorl" in tto July 
73. 



OCTOBER 1966 



10? 







r.2 -I 



LO - 



m 



0,8- 



0.6- 



u 



0,4 



as 



ZENER 
PLATEAU REGION 



KKEE REGION 




— ' 1 * r — ' rr — ■ 1 ■ 1 

f) 2 4 «f B 10 

VOLTAGE APPUCO TO ZENER 

Fig. 4» How zener current depends on applied volt* 
age for a 10 watt zener. The rise beyond the knee 
IS so sharp the zener must be supplied from o cur- 
rent-limiting resistor or circuit 

curve in wliich the cm rent first begins to rise 
is called the zener knee, and the normal oper- 
ating region is called tlie zener plateau. The 
useful plateau is limited at one extieme by 
the current required to keep the zener action 
alive, and at the otlier by temperature in- 
crease sufficient to destroy the zener. 

The zener regulating voltage depends on 
how thick the PN junction is. If the FN junc- 
tion is very narrow, the zener will regulate at 
a low voltage; we leave these details to the 
manufacturer. But depending on the structure 
of the zener it may show an increase or a de- 
crease of voltage as it gets warmer! Zeners 
under about 5 volts will show a decrease in 
voltage, over about 5 volts a rise, witli m- 
creasing temperatme. A happy choice of volt- 
age and current will give a zero drift: 40 mA 
at 4,8 volts, to 3 mA at 6 volts. Review the 
manufacturer's specs if real stability is re- 
quired. Two or more zeners in series will show 
a smaller temperature voltage drift tlian a 
single equivalent higher-voltage zener. 



Type 

m4728A 
1N4733A 
IN4735A 
1N4739A 
1N4747A 
1 N4752A 

1N957B 

1^430T6B 
I N2970B 
1N2804B 

Z4XL6.2 
24XL6.28 



Price 

SK93 
K93 
L93 
1.93 
1.93 
t.93 

2.95 
3,70 
7,30 

1Q.65 

0.75 

0.84 



Norn. Volt- 
ogc Test 
Current 

76 mA 
49 mA 
41 mA 

28 mA 
12.5 mA 
7,5 mA 

1 8, 5 m A 
37 mA 
370 mA 
1.85A 



1 20 
20 



mA 
mA 




Fig, 5. TypeSj prices^ and characteristics of some 
typical zeners. Note variations in dynamic resist- 
ance. 



Zener specifications 

All zeners are supplied with a voltage rat- 
ing, and a tolerance. Like resistorSj the stand* 
ard tolerances are 20%, 10%, and 5%. The 
nominal values are usually chosen in the same 
way as those for resistors, resulting in voltage 
ratings tliat should sound veiy familiar. The 
system is based on the twelfth rnc>t of ten for 
10% zeners, so you will find for instance, 3*3, 
3.9, 4.7, 5.6, etc. J voltage ratings* Fig. 5 lists 
some zeners and their properties. If you are 
trying to regulate to a critical voltage, a ger- 
manium or a silicon diode may be placed in 
series with the zener (small increment) or 
in series with the load (small decrement). 

The temperatme drift problem can be min- 
imized by keeping the zener cool. Tliis con- 
flicts with power handling ability but tends to 
guarantee long hfe despite experimental acci- 
dents. Like all semiconductor materials, if a 
zener PN Junction gets too hot, the doping 
atoms begin to jump into new sites. This is 
very bad for the zener 1 Since the junction may 
withstand temperatui'es as high as 200 de* 
grees Centigrade, zeners axe not remarkably 
fragile. But they cannot withstand the kind 
of overload even small power supplies can 
produce* 

Zener wattage, as in any resistor, equals 
voltage across the zener times current through 
the zener. Check manufacturer's specs if much 
power is to be handled or if operating near 
maximum ratings. For breadboard and quick- 
and-diity^ construction the fingertip test will 
do: too hot for a five-second fingertip touch 
equals too hot 

The zener 's ability to stabilize and filter a 
power supply output is indicated by its dy- 
namic resistance. Low dynamic resistance is 
desirable. Suppose you wish to have power 
snpply output stay within one- tenth volt of 
nominal in spite of 100 mA variations in cm- 
rent By Ohm's law that works out to one 
ofun: tliis is the dynamic resistance required. 
High wattage zeners, near 6 volts\ have better 
d>Tiamic resistance than any others; high volt- 
age zeners have very poor dynamic resistance 
but are not required for most semiconductor 



Fig. 6. Equivolent cir- 
cuit for estimating 
how much o zener 
regulator will reduce 
the percentage end 
amplitude of power- 
supply hum. 



POWER SUPPLY HUM 
VOLTAGE MEASURED HERE 

O 




CURRENT LIMITING 
SERJES RESISTOR. 
MORMAUJr V FEW 

TENS or 

OHMS 



^OfYNAMlC RE 
' SFSTANCE OF 
*ZOtER. 
! USUALLY A 
tFEW QHWS. 




VOLTAGE DiVIDEft EFFECT 
REDUCES PERCEN"mGE 
HUM AT ZENER TCRMIN4L 



110 



73 MAGAZJNI 




circuits. 

The practical effects of dynamic resistance 
can be brought out by drawing equivalent 
circuits to show what's involved. An equiva- 
lent circuit is soniclliing used by engineers to 
simplify circuit problems. The dotted box 
suggests ^\ve imagine the actual device acts 
like what's in there." From a hum viewpointj 
the zener improves tlie situation as if the en- 
tire ciixuit were a voltage divider. The upper 
resistor is the required series resistor R^ and 
the lower resistor is tlie zener s dynamic re- 
sistance. Tills is usually listed in the catalog 
entry. If the dynamic resistance is one ohm, 
and the series resistor is fifteen ohms, the usual 
way of working out voltage-divider circuits 
tells us the hum will be reduced by a factor 
of 16. That doesn't remove it! Typical hum 
from a capacitor filter low-voltage supply is a 
half volt to three volts. This would result in 
anticipated hum figures 30 to 200 mV; stiU 
plenty of hum. 

Fig, 7 shows the way to estimate how much 
the zener voltage will change under load. This 
figure is very different from the actual circuit 
so do not feel stupid if it's not clear! Try this 
with an actual zener when you Ve finished the 
article. Measure the zener voltage at a current 
near the knee. Measure it again at near maxi- 
mum zener current. It will be higher. Now 
write down diat higher voltage next to the 
'inside battery/ If yon draw current from this 
equivalent circuit, the voltage will drop be- 
cause of losses across the inside resistor. This 
is just what the real zener circuit did: the 
small zener current corresponds to maximum 
load condition from tlie equivalent circuit. 
The voltage change divided by the current 
change gives the value of the series resistor. 
It wiU be the dynamic resistance again. This 
shows that knowing the dynamic resistance is 
very useful in reckoning the effects on regu- 
lated voltage of changes in load cmrent. 

Zener noise 

The useful ability of zeners to conbol cir- 
cuit hum and noise is somewhat compromised 
by their natural ability to generate signals of 
their own. The zener regulating process is hke 
an electrical discharge, and can produce simi- 
lar noise. Good zeners produce very fittle 
noise, but some may become quite loud in the 
zener knee region. If your new circuit seems to 
be troubled by erratic frying and hissing 
noises, and this is traced to the zener regula- 
tor; the two solutions are increasing zener 
current to keep it out of the knee region, or the 
addition of a capacitor to take up the noise. 
Try 0.1 viF to start. 



Fig- 7. Equivalent cir- 
cuit for reckoning 
voltage drop with in- 
creased (ooding of a 
zener regulated sup- 
ply. 



RESISTOR tOUAL TO 
ZENER Dr^AMlC RESIS- 
TANCE CAUSES OUTPUT 
VOLTAGE TO FALL WITH 
INCREASED CURRENT 



X 



A^*v 




I'jMAGlKARY PERFECT BATX 
I W)40S£ VOLTAGE ALWAYS 
! EOLM^LS MAXIMUM lENER 
I VOLTAGE. 



OUTPUT 

TEFtMIHALS 
OF 

REGULATED 

supfn.Y 

Q 



Varactors are reverse-biased silicon diodes. 
Since zeners are also reverse-biased silicon 
diodes, do they have an associated capaci- 
tance? They certainly do; it may be as large 
at .01 mF. This capacitance is unimportant in 
normal operation, and probably has a benefi- 
cial effect in reducing zener impedance at 
high frequencies. Perhaps tliis capacitance can 
be put to other uses! Might be an easy way to 
double up to 40 from 80 meters. Another pos- 
sible apijUcation would be oscillator tuning; 
perhaps a cheap Eener would work better than 
a cheap siUcon diode. All tlus brings to mind 
Fisk's interesting article in the March 1966 
issue of 73, 

Zener regulator design 

All zener circuit designs depend on the 
same basic facts of the zener's voltage, toler- 
ance, wattage rating, dynamic impedance, and 
perhaps temperature drift. The worst case 
from the zener's viewpoint is DC power reg- 
ulation, with a steady current supply from a 
voltage source capable of destroying the zener 
if the series resistor fails or is shorted. Zener 
regulators are very useful and deserve a close 

examination* 

Only professional engineers should design 
zener circuits to operate at the limits of the 
zener's capabilities. The amateur, by leaving 
generous margin for error, can simpHfy the 
design problem to a point where only the 
simplest math and less than complete infor- 
mation on the zener's capabihties will be suffi- 
cient for a reliable design. Apart from possibly 
very serious misunderstandings on the ama- 
teur^s part, the major troubles that might arise 
are the relatively generous tolerances on most 
inexpensive zeners, the wattage problem^ and 
voltage change under load resulting from 
dynamic resist ance. 

The design process commences with finding 
some working figures. Refer to Fig. 8^ a design 
sketch made just before carrying out the fol- 
lowing procedure. Power supply voltage, zener 
voltage, and load current information are col- 
lected, along with their estimated maximum 
and minimum values, A class B audio ampli- 



OCTOBER 1966 



111 



Frg, 8. Designing a re- 
ffable zener regulator. 
The question marks 
indicote values to be 
worked out. 



UIM fa4V 



AT ? WATTS 



V^ •7VOLTS 
AT? WATTS 




1 



t|, 'AO mA 
WAX. 400 mA 
MIM. 10 tnA 

MUST NOT 

OtCCED lOV 
0*t RM_L 
SELOW 7V 



fier of a few watts capability could account 
for the fairly large current variations shown in 
the diagram; this i.s a rather extreme case. But 
it could happen! If the load were a receiver 
smalK^iignal circuit, an oscillator, or a trans- 
mitter VFO; the load would be practically 
cx)nstant. After collecting this infonnation 
from figures, estimates, educated guesses, and 
by breadboarding, the circuit is designed on 
average values. When a series resistor and a 
zener are chosen, their anticipated properties 
are checked against possible extreme condi- 
tions of voltage and amperage. 

Variations in load current are made tip by 
apposite variations in zener current Minimum 
zener current flows w^hen maximum load Lur- 
rent is taken from the regulator. This adds up 
to the first requirement for the zener: it must 
carry a current greater than the anticipated 
load swing. The regulalion fails if the zener 
is starved into the knee region, and if the 
zener is overheated by excessive current, 
catastrophe is likely. Often a well-placed large 
capacitor in the load circuit will absorb the 
drastic swings. The zener required in Fig. 8 
must carry more than the swing of 390 mA. If 
the minimum and miiximum loads were both 
©-eater by 1 A, the swing would remain the 
same and so the zener minimum current re- 
quirements would be unchanged- However, 
with increasing loads flowing past tlie zener, 
a point may come at which turn-on or turn-off 
ol the circuit results in transient overloading 
of the zener. 

A safe minimum zener current is 10% of its 
maximum rating, A fresh zener accompanied 
by manufacturer's specs may be used at much 
lower levels, taking the specs as a reliable 
guide. For surplus zeners the 10% lower h'mit 
is recommended unless a test shows tlie par- 
ticular zener will stand further starvaliun. 
Since the voltage requirements are already 
determined, the clioice is made on the basis of 
wattage. Don*t be afraid to use an oversize 
zener; it's safer and the larger zener will have 
a lower dynamic resistance. The absolute 
minimum wattage required equals the maxi- 
mum possible voltage across the zener times 
the maximum expected current through it. 



There seem to be no 5 watt zeners; for most 
regulator purposes the choice is limited to 1 
or 10 watts. Or 50 watts if you wallet can T 
stand the drain. The zener in Fig. 8 should I 
carr>^ about 450 mA under minim imi-Ioad 
conditions; at 9 volts that works out to just | 
under 4,5 watts. A 10-watt zener is indicated. 

Now the series resistor R^ can be chosen. 
The voltage at its upper end is fixed by the 
power supply, and at its lower end by the 1 
zener. The series current is the maximum load I 
current plus the minimum zener cmrent | 
finally decided on • . , in the case of Fig. 8 
this was a total of 450 mA. This same cur- 
rent flows if the load drops to 10 mA, since 
the zener now takes 440 mA. Knowing the 
voltage across the resistor, 24 volts minus 8.2 
volts, or 15,8 volts, it appears that a resistance 
of 35 ohms and about 7 watts is the minimum 
value. 

This leaves no margin for error. A better 
choice is an Ohmite adjustable wire-wound 
resistor, 50 ohms, 25 watts. More than half 
the resistor will be in the circuit. If only half 
or 25 ohms were used, it would still be rated 
at 12.5 watts, so that w^th this choice the suc- 
cess of the design seems probable* 

Now we return to the zener. Any electrical 
slop in the design can be taken up by the 
resistor, and we know that a 10-watt zener is 
required. Referring to the catalog, we find a 
1N2973B, 9 J volt B% zener. We expect the 
circuit can withstand the possibly slightly high 
voltage. If not, we'll change the circuit* We 
choose a zener at the liigh end of the range 
because its voltage will drop under load: a 
dynamic resistance of 2 olims means 2 volts 
drop per amp decrease in zener current, or 
in the case of Fig* 8 the voltage will swing 
over a range of 0.23 volts. Adding to this the 
.45 volts possible error due to zener tolerance, 
and adding that to the 9.1 nominal zener rat- 
ing gives about 9.8 volts as the largest we 
should expect to see in the cLrcuit. Subtracting 
the same figure from the 9.1 nominal figure 
gives a minimum of 8.4 volts in the case of an 
extremely low valued zener. These results are 
within the previously decided requirements* 

There is still the question of changes in 
power supply voltage. What happens if line 
voltage changes drastically? This cannot be 
answered simply; some line voltages are more 
changeable than others! In Fig. 8 a 10^ vari- 
ation either way was just picked out of the 
air. This is probably large. Now if the zener 
voltage is fixed at 10 volts, wliich it will never 
quite reach in the actual circuit, and if the 
supply voltage drops to 20.4 volts; the series 
resistor being at 35 ohms with 10.4 volts 



}n 



n MAGAZINE 



across it now passes only 335 mA. Not enotigh, 
so we adjust the resistor to 23 ohms, and it 
now passes 450 niA, But now we must try 
the other extreme: tlie power supply voltage 
rises to 27.6 volts and we suppose the zener 
to be an 8.4 volt type. Then we find 19.2 volts 
across a 23 ohm resistor. That is about 840 
mA. The zener won't overheat if it is properly 
mounted, but tlie resistor must dissipate 16 
watts. Since less than half of it is carrying 
current, we must go to a smaller resistance at 
the same wattage in order to get enough dis- 
sipating surface. The choice is a 25 ohm 25 
watt resistor, still adjustable. Or if youre a 
little apprehensive about going that close to 
the limit, a 50 ohm 50 watt resistor can be 
purchase at an 83 cent increase in price- 

That completes the design. This process 
avoids the following kinds of grief: Zener fail- 
ure due to overheating; zener voltage out of 
specs; circuit loads zener regulator into tlie 
knee region; regulator fails due to star\'ation 
or overheating at extreme line voltage values. 

Correcting zener voltage 

The combined effects of high prices and 
large tolerances are hard to beat! But a re- 
sourceful amateur nerd not lose a project just 
because his nearest zener isn't quite near 
enough* Zener voltage can be adjusted up or 
down by correct use of small gei-manium or 
silicon diodes, The price is a slight increase in 
dynamic resistance and in temperatme drift. 
Some knowledge of the nroperties of forward- 
biased diodes is requiied. 

A silicon or germannim jnnction diode, 
carrying a forward current of 10 to 100 mA, 
depending on its size, has properties very 
hke those of a low-voltage zener. In fact, there 
are no zeners under about three volts, and 
diodes are used in just this way to fill the re- 
maining gap down to near zero. Beyond the 
early stages of conduction, a few microamDs 
or mils, the diode voltage changes very little 
with current Its dynamic resistance is quite 
low. Diodes can be used in zener circuits as if 
they are little batteries, to achieve a slight 
increase or decrease in apparent zener voltage. 
The voltage measured across the zener itself 
is not affected. 

The voltage at which the diode regulates 
depends on its material: germanium or silicon. 
A germanium diode well into conduction will 
show a stable voltage of around 0.3 volts; a 
silicon diode regulates above 0.7 volts. A 
transistor base-emitter or base-collector iunc- 
tion could be used in place of the real diode; 
it's a FN junction too and will show the same 
behavior. 

To achieve a small increase, the diode is 




SERIES DIODE VOLTAGE 
ADDS TO Z^Hgn 



VOUAfiE. 




M 



SERIES DIODE VOLTAGE 
SUBTRACTS FROM 
ZENER VOLTAG^E, 



Fig. 9, The effective regulating voltage con be 
adjusted by correct applfcation of ordinary ger- 
manium or silicon diodes, 

placed in series witli the zener, as sho\^Ti in 
Fig. 9A. The reverse*biased zener and the 
forward-biased diode point in opposite direc- 
tions. The dravvnig is arranged so tliat posi- 
tive current— a conx^ention— flows down. Fig. 
9B shows the diode in series with the load, 
so that its voltage subtracts from the zener 
voltage. They seem to be pointed in the same 
direction, hut the cmxent flows against the 
zener and with the diode. This is certainly 
confiising and will require some careful think- 
ing. Try it; make your mistakes on a bread- 
board where ihey show clearly and are inex- 
pensively remedied! 

Amplified zeners 

Being relatively high priced and having 
rather large tok^rances, zeners may seem rather 
useless to many amateurs. But a small^ inex- 
l>eiisive zener can be combined with a tran- 
sistor, making a simple two-terminal circuit 
that will slund in very well indeed for a 50- 
watt or even larger zener. This particular 
tj'ansaction shows an unusual measure of profit; 
besides greatly reduced price and substantial 
easing of power limitations, dynamic resist- 
ance may be improved and becomes little 
afl'ected by using diodes in series with the 
zener to build up its voltage. The effects of 
temperature upon voltage are increased hut 
this will rarely be important. The current han- 
dling ability is muUiplied by the transistor % 
but the temperature drift is only that of the 
individual diodes in series. 

For instance, a Texas Instruments 2N251A 
at $2.25 plus a General Electric Z4XL6-2 at 
75<f adds up to $3.00 for a shiny new, some- 
what adjustable zener, rated about 50 watts 
depending on the beta of the transistor. 
TWs is comparable to the 1N2804B, priced at 



Fig, 10. Schematic of 
on amplified zener. 
It's all there! 




OCTOBEie 1966 



113 



s---- J^ - . . .f-J-J- ■ -, 








Vy*^ 'S^in-^ W 







^M#. 







. ■ • --■-■•-.•■^;- 



Fig. ] T. A real amplified zener, and its measured 
characteristics. This one is good for about 20 
watts. Made of junk box parts^ its estimated cost 
is 50^. 

$10,65. That's what makes amplified zeners 
interesting! 

The complete circiiit is shown in Fig. 10 • 
It does seem rather bare in comparison with 
most ti-ansistor circuits, but everything that's 
really required is tbere; one zener and one 
transistor. This two-terminal circuit closely re- 
sembles the emitter follower regulator, and if 
a resistor were added from the zener diode/ 
transistor base connection up to a higher volt- 
age to ensure liberal zener current, it would 
be an emitter follower regulator. But the re- 
sistor can be omitted if the amplified zener^s 
knee region is avoided, and then the current 
divides between the transistor and the zener 
according to the beta of the transistor. 

An amplified zener is shown in Fig. 11, This 
one costs an estimated 50fJ and gives very good 
test results. Its knee region seems to end at 
about 4.2 m A and the actual zener diode is 
not overheating at 1.6 amps regulator current. 
A current increase to about 1.6 amps boosts 
the voltage from 5,6 to 6,8 volts, for an aver- 
age dynamic resistance of 0.67 ohms. Using 
the voltage-divider method and hum input- 
output measurements, its dynamic resistance 
at 1.6 amps is 0,59 ohms, Tlie very best zeners 
are little better than that. There is one hid- 
den pitfall: the transistor's leakage current 
increases with temperature. This extends the 
knee region to higher current values. 

This is how the current division works out* 
There are only two terminals; the current must 
go in one and out the other. It takes two 
routes in between. Suppose the base-collector 
zener is carrying m milliamperes. The tran- 
sistor base-emitter function supphes this cur- 
rent, and as a result an additional current, 3 



times larger, flows from emitter to collector of 
the tiansistor. The total current I is the sum 
of these two, so that we write 

I = m + 3m = m (1 -f 3) 

The one plus beta in the parentheses is not 
particularly different if we leave out the one, 
provided the beta is greater than ten or twenty. 
It usually is in a usable transistor; the differ- 
ence between ten and eleven is 10^, smaU by 
electronic standards. For most purposes it's 
simpler yet true enough to say all of I goes 
through the transistor, the circuit regulates at 
the zener voltage plus the transistor BE volt- 
age, and the zener heating current is I divided 
by p. The error is trivial. 

For example, the Z4XL6,2 is rated at one 
watt, tlie 2N251A at 90 watts, and suppose 
a 3 measurement under approximate operating 
conditions gives a result of 50, well within 
specs, Remember that 3 is quite evanescent, 
depending upon collector current in addition 
to great variations between transistors of the 
same type! The maximum allowable zener cinr- 
rent is 160 mA, since ,160 amps times 6.2 
volts equals the rated one watt. Then 50 times 
160 mA gives a maximum of 8,4 amps current- 
The amplified zener regulates at 6.4 volts, 
since the live germanium transistor will show 
about 0,2 volts from base up to the emitter 
which is added to the zener voltage. If you 
really want to dissipate 50 watts, tlie transistor 
should have higher 3 or a lO-watt zener should 
be used; stay away from calculated limits! 

The dynamic resistance of the amplified 
zener will be the inside real zener^s dynamic 
resistance divided by the transistor 3^ This 
works out to one-fiftieth of 9 ohms: 0.18 ohms. 
This value is so low that the power transistor's 
characteristics may enter into the final result; 
the final value vdll still be well under an ohm. 
This result is not appreciably spoiled by add- 
ing series diodes to pad up the zener's appar- 
ent voltage. 

As the current tlu'ough the amplified zener 
is reduced toward zero, the real zener and the 
power tiansistor both weaken. The combined 
effects are rather uncertain, so that bread- 



Fig, 12, A pofr of ze- 
ners in series to pro- 
vide both positive and 
negative voltages with 
respect to circuit 
ground, using a single 
power supply. 



o 

+ 

UNR£G. 
SUPPLY 



6V 
Z£NER 



1 



+ 6V TO 
CIRCUIT 



LOAD oRcurr 

REQUIftlMG 
BIPOLAR SUPPLY 



I 



TO aacurr 

GND. OR 
CHASSIS fT7 



3V 
ZENER 



-iV TO 
CIRCUIT 



114 



73 MAGAZINi 



boarding with the actual components is a good, 
safe practice. Find the knee by measurement; 
remember that a capacitor across the zener 
will reduce its noise generating GapabiUties! 
A 6 mF electrolytic capacitor eliminated a 
rushing noise near the knee region in the am- 
plified zener shown in Fig. 11. 

Other zener applications 

Zeners do not go very well in parallel One 
will tend to hog the current. There is no need 
for parallel zeners an>^vay; an aniplified zener 
will do a better job. But zeners can be con- 
nected in series to provide two or more regu- 
lated voltages. And in this case the ground 
can be between the 2eners, rather than at one 
end of the power supply. If yoti ground both 
points, it won't work! 

The design of switching circuits is consider- 
ably simplified if the usual collector voltage 
supply is supplemented by a lesser voltage of 
opposite polarity. The second supply is used 
to drain off unwanted leakage currents, turn 
diodes and transistors hard off, and for other 
applications. This relatively slight increase in 
the designer's armament eases many tough 
circuit problems. By using a pair of zeners in 
series, the desirable pair of voltages can often 
be obtained without going to the time and 
expense of a separate second power supply 
and all its problems of cost, space, weight and 
regulation. Fig. 12 shows how simple tliis 
arrangement is. 

Without a load circuit, the same current 
flows through both zeners. If some current is 
side-tracked around either zener, the voltage 
across it remains constant. The regulation isn't 
disturbed at all if some current is taken out 
around both zeners, and this is the normal 
application- The usual consideraHons about 
starving and overfeeding zeners are applicable 
here, and the beginning designer should re- 
member that the two supply circuits don*t 
necessarily require the same currents at the 

same time* 

The zener diode shows little promise as a 
limiter and no schematic for this application 
is inchided. Ordinary diodes are distinctly 
superior. Zeners require too high voltage: 3 
volts or more. In normal circuits that's in the 
liigh-power range. The clipping should be 
carried out well before the signal gets this 
large. Also, the zener will clip at normal sili- 
con diode levels as soon as its PN junction is 
forward biased. Additional diodes would be 
requiied to prevent this, unless unsymmehiral 
clipping were intended. Zener clipper circuits 
appear impractical. 

The only remaining field in which vacuum 
tubes retain some superiority to solid-state 

OCTOiER 1966 



Fig. 13- Zener diode 
biasing for on RF 
power vacuum tube. 
Bypass capacitor rec- 
ommended^ appropri- 
ate for operoting fre- 
quency. 



WF PA 
TUBE 




SCRCEM, 

t PLATE 
CUftREHTS 



KEEP-ALIVE 
CURRENTS 



amplifiers is large-signal if power amplifica- 
tion. The zener diode can fill a very useful 
spot here. It can replace the eatliode bias re- 
sistor, offering a bias voltage quite independ- 
ent of tube current. Fig. 13 shows a zener in 
this application. 

Because the zener acts like a battery, most 
of the high voltage is taken up by the vacuum 
tube. The zener merely guarantees the bias. 
It never runs down or emits corrosive chem- 
icals, and has a lower internal resistance than 
the batteries used for this application in the 
old gear described just after W^^'2. If the tube 
is to be biased to cutoff, the zener can be 
suppHed with enough current to keep out of 
its knee region by means of a resistor up to 
the high voltage or over to the adjacent tran- 
sistor circuit wliich should be pro\dding the rf 
to the power amplifier. The zener should be 
bypassed for r£ 

Zener meter 

A zener diode can be wedded to a meter 
circuit with very useful results. To understand 
the utility of this match look at the usual 
linear meter scale. Suppose it reads to 20 volts- 
A one-volt reading will be way down at one 
end, and a lower range is required to make it 
readable. A small change huge percentage in- 
crease at the low end equals in scale space a 
small change tiny percentage increase at the 
high end. That*s not a very equitable distribu- 




REVERSE 
DEFLECTION 



S ID 19 

APPLIED VOLTAGE OF 
CORRECT POUAKITY 



Fig. 14. How an improved meter might be cali- 
brated to show small and large voltages with com- 
porable accurocy. Reverse voltaga does not bang 
the needle backward. 



115 



1 



eoK 



Fig. 15. A circuit that 
wrfl produce the char- 
QCteristics shown, 



lao K 



3V 
lENElt 



Z4 K 




LABflCriTE 



Hon I For example, it would be convenient to 
cliecic tiansistor emitter-base and emitter- 
collector voltages witliotit changing ranges, 

Tlie required benefit is achieved if the cir- 
cuit can be made to show variable meter sensi- 
tivity. Fig, 14 shows a realizable result, de- 
tailed below- The first half of the meter scale 
is taken up with the zero-to-five volts range. 
The five-to-twenty volts range occupies the 
second half of the scale, without switching. 
The poor sensitivity to voltage applied in the 
wrong direction is a valuable by-product of 
scale tailoring with a zener diode. 

At fiist glance tliis circuit appears to have 
been designed by a net\vork expert. A closer 
look reveals that tlie values of the resLstors 
may be deduced, one at a time, by thinking 
out the inside requirements of the circuit. Rl 
and R2 will fall first. If the meter is to read 
5 volts at half scale with 5 volts applied, Rl 
plus R2 must come to 2()()kQ since dus will 
pass the required 25 microamps. The Lafay- 
ette meter^s resistance of IkQ is insignificant 
in comparison to this value. Supposing at 5 
volts die zener hasn't quite broken down, it 
must have just 3 volts across it The voltage 
across Rl must be 2 volts, and at 25 micro- 
amps the resistance must be 80kQ. That leaves 
120kQ for R2 since the pair must add up to 
20()kQ. We aheady know the 2:ener; the prob- 
lem fs two -thirds solved. 

Now we proceed confidently to the deter- 
mination of R3. At 20 volts applied the meter 
reads full scale, therefore is carrying 50 micro- 



Fig, 1 6. A zener diode 
combined with a tran- 
sistor to make a con- 
stant-current regulat- 
ing circuit. 




CONSTANT 
CUftftENT 



amps. This current through R2 must bring the 
junction between Rl, R2 and the zener to 6 
volts. Now there must be 14 volts across Rl 
and that yields 175 microamps through it. Tlie 
meter gets 50; 125 microamps pass througli 
the zener and its series resistor. We have it I 
From the junction through the zener we lost 
three volts, by design; the remaining three 
volts at 125 microamps Rxes R3 at 24kQ, 

A breadboard check shows that the cirtuit 
behaves about as shown in the graph. This 
graph preceded the desi^, and the actual 
circuit is influenced by the characteristics of 
the zener in its knee region* Because the zener 
comes into conduction gradually as aoplied 
voltage is increased, rather than abruptly, the 
actual scale change from steep to flatter occurs 
along a rounded cun^e. A new calibration scale 
must be constructed emnirically* That is, each 
point must be located by applvinf; the indi- 
cated voltage and marking or listing the re- 
sulting meter deflection. This good idea needs 
further development; it requires enough cur- 
rent to disturb many transistor circuits. 

The constant-current generator circuit close- 
ly resembles the amplified zener. Only a re- 
sistor has been added. But the constant cuiTcnt 
generator guarantees a certain fixed current, 
rather than the amolified zener's refiable volt- 
age. Its operation depends on the resistor; tlie 
zener provides a reference voltage and the 
transistor, actitig as an emitter follower, hr)lds 
that voltage across the resistor. The resulting 
cui'rent, determined by 01im*s law. is inde- 
pendent of voltages applied to the outside 
circuit terminals if the transistor is biased into 
its operating range. 

A working circuit is showm in Fig, 16, Re- 
member that the power dissipated by the 
transistor is determined by its collector current 
and voltage, not by the values at the rest of 
the circuit. As in the amplified zener, if the 
transistor 3 is larere enough the zener ciurent 
may be ignored. The computation proceeds in 
this wav: the 6 volt zener fixes the voltafie 
across the resistor at 5.8 volts, because 0,2 
volts is lost across tlie base-emitter function 
of the germanium transistor. If a silicon tran- 
sistor were used, the resistor would see 5.3 
volts. Since a cunent of 100 mA is to be guar- 
anteed, the resistor must therefore be 58 olims. 
A fixed current of 10 mA \^^ould require a 580 
olim resistor since the voltage across it is held 
constant. Rut that minht not work so well since 
the zener could be star\-ed for current; perhaps 
the zener could be biased elsewhere and its 
voltage earned o\'er to the transistor base. 

This is an excellent circuit for eliminating 
hum. The hum curi'ent cannot pass the con- 



116 



73 MAGAZtNi 



+ 



POWER 
SUP**LY 



S0?IES RESSTOft Of* 

coftisTAnT-euRRe**T euncurf 
vw — 



EQUftL TO ZOC« Cl**RENT| 



RATED 

ZENEH 

CURRENT 






POWER 
TRUNKS TOR 



SMALL 
TRAwSStOft 



I AT LEAST 
10.f 

Fig. 17. A very close relative of the amplified ze- 
net. Acts like o voriobfe zener. 

stunt current circuit: no 1mm! But before this 
circuit can be put to work in a usable power 
supply, it must be provided witli an appro- 
priate load. The fixt^d current will generate a 
large voltage acros.s a large resistor, a smaller 
voltage across a smaller resistor, and a zero 
\ ullage withmit blowing up anything across a 
sliort. This tail-safe feature can be retained 
while correcting the terrible regulation prob- 
lem by adding a zener regulator. The constant 
current is just right for biasing zeners; it is 
inserted in place of the usual series resistor, 
and a really good supply results. You should 
know how to do that by now! 

Finally, the last circuit is a reali^ahle sub- 
stitute for a continuously variable zener. It 
looks very much like a Darlington pair used 
as an emitter follower. A CTurent of 10 mA or 
so from a zener regulator i:juts a fixed voltage 
at one end of a pot, decreasing to zero at the 
ground end. This voltage is stable if very Uttle 
current is drawn. But the cioTent required by 
the Darlington pair to regulate at a certain 
voltage will be the through or zener-like cur- 
rent divided by the p of the first transistor, the 
resu't divided again by the (3 of tlie second 
transistor. A milliamp will detennine one to 
ten amps! The illustrated circuit will regulate 
from about one to 15 volts. The capacitor is 
required to take out hum coming around 
through the zener reference voltage source. A 
supply using tlie two circuits above shows 
regulation as good as simple feedback-regu- 
lated supplies, combined I mm and noise of 
about 0.6 millivolts, and ad|ustabilily over n 
wide range, 

Siiq:>lus zeners 

Zener diodes are available at prices well 
under par from se\( i ul somces. The routes by 
which these zeners enter the surplus and ham 
markets are not at all apparent , but it seems 
that in many cases these zeners are rejects 
having no place in any electronics gear, ama- 
teur or otherwise. It also appears tluit some 
suppliers— note plural!— do not test their zeners 



as well and carefully as advertising statements 
seem to indicate. 

Assorted zeners from one supplier were 
tested for zener voltage and dynamic resist- 
ance. Most tended to regulate in the general 
20% region, but a few were drastically off. 
Many of these zeners, 10 watt stud mountiag 
types priced under a dollar each, had fairly 
high dynamic resistance. Perliaps that is why 
they were available! A second cuUection, about 
30 assorted zeners adding up to the attractive 
price of $10 phis shipping, appeared consid- 
erably less economical after careful checking 
and tests. Some were mounted backwards in 
their cases, many showed poor regulation, a 
few were phenomenally noisy, others did not 
zener at ail, and one had a broken lead. The 
more expensive varieties did not seem to aver- 
age any better than the cheapest ones. There 
is a moral here. If you are going to use surplus 
zeners, check regulating voltage, dvmamic re- 
sistance, and noise characteristics of each zener 
before yon put it in that nice new circuit. 
Don't take it on faitli; the chances that it is 
not as indicated may be as bad as one in two. 

This experience suggests tliat the most eftec- 
tiv^e way to buy is to purchase new stock ze- 
ners, or else test before buying. It may help to 
initiate a general practice of testing zeners 
promptly upon receipt, and returning bad ones 
to the supplier. Be certain the test is correct! 
Or perhaps you have found a good source of 
tested surplus zeners; if so, make tlie most of 
it and tell yom* friends. A zener is a zener, and 
it^s the device, not the labels that is required 
in the circuit 

Testing surplus zeners 

A batch of surplus zeners can be tested 
most effectively if the operation is performed 
in several steps. The first pa.'5S eliminates the 
obvious duds, the second sorts out the remain- 
ing zeners into broad voltage ranges, A third, 
perhaps, determines if a particular zener can 
be used in a specific appliciUion. 

Several instruments are required for com- 
plete testing. Also a few resistors and clip 
leads, a place to work, some scratch paper, 
and marking paint A high-sensiti%dty multi- 
mt tt^r or a dc VTVM serves for voltage meas- 
urement. Another multimeter or a miUiam- 
meter provides for current measurement. An 
optional ac \'TVM is useful for checking dy- 
namic resistance by the hum voltage divider 
method. A signal tracer will sei've very well 
for detecting the sHglit hiss a few zeners show 
in the knee region, or the raucous racket at 
Ingher ctirrent levels indicating tlie zener 
should be discarded. Finally, a magnifying 
glass assists in detecting mechanical faults on 



OCTOBER 1966 



117 



n 



the surface of the package. 

The surplus market is low man on the totem 
pole. It's quite safe to expect a specific zener 
has something wrong vvitli it, which brought 
it to the supplier and then you^. The testing 
operation is a sort of detective game played 
to find out if the fault will or will not inter- 
fere with its use in a piece of ham gear. This 
game can be played most productively if the 
goals are known. First, does it show semi- 
conductor properties at all? Second, what do 
they seem to be? Finally, does a closer inspec- 
tion show they are really there, and that ob- 
vious faults are absent? 

Modem technology and the manufacturers 
have conspired to make this game more diffi- 
cult than it might be. A given zener may be a 
double-anode device, usable in either direction. 
Or it may be a zener and a diode, practically 
tlie same tiling but rather different in intent. 
And there is a chance it is an amplified zener: 
a zener and a transistor in one package, The 
amplified zeners seen so far have been high- 
power devices^ but this may change any time. 

A first inspection serves to eliminate broken 
zeners, ones mth bad leads, cracked eases, and 
other faults. An obviously abused condition is 
certainly grounds for rejection. At this time the 
wattage can be estimated by comparison with 
know^ zeners and catalog descriptions. A few 
zeners are shown in Fig. 2. Low-wattage accu- 
rate zeners may be plaml in large cases for 
better temperature control; high- wattage ze- 
ners are indicated by the provision of some 
means for mounting to a heat sink. 

Then the power supply is set np with its 
negative output temiinal to ground. A resistor 
is placed in series with its positive terminal, 
chosen to limit the current to near 10 milU- 
amperes. A 40 \ olt supply would require about 
4000 ohms, anything over a half watt would 
do. The zener goes between the output end 
of the resistor and giound. Regardless of its 
condition it cannot receive more than 10 mA; 
this is a safe arrangement 

The first test is to measure the lowest volt- 
age across the zener at this current, trying 
both directions. If there is a polarity mark or 
band, the least voltage should be seen when 
the band or "cathode" end is toward negative 
ground. If the voltage is under about 0.6 volts, 
the device is not a zener and further testing 
is not required. If it is in this range, and if 
doubling the current by halving the series 
resistance from the supply produces only a 
small increase in voltage, the device is show- 

'^f course, many zeners reach the surplus market as manu- 
fachirers' over-mn, production ends, etc. These zeners, 
which are available from many suppliers, are generally 
good, new diodes. Ed. 



ing proper characteristics for a forward-biased 
silicon FN jiniction. If tliis cannot be achieved, 
it may be a faulty device, or it may be one 
of the more complex varieties, mentioned but 
othen%dse carefully avoided in this article. 

A breakdown test is now appropriate. The 
cathode end is turned toward the positive sup- 
ply^ and a measurement of voltage gives the 
approximate zener regulating voltage. If the 
resulting voltage is the power supply voltage, 
tlien no current is flowing and tlie device may 
be a rectifier whose inverse voltage, or a zener 
whose breakdown voltage, exceeds that avail- 
able. A current doubling should, again, have 
very little ellect on the stabilized voltage. This 
test indicates that the device shows zener 
characteristics. 

Knowing the approximate zener voltage and 
wattage, the supply circuit can now be revised 
to bias the zener to anticipated normal oper- 
ating conditions. At this time the dynamic 
resistance can be estimated by the hum reduc- 
tion method or by the voltage change over 
cinrrent change method. Typical values for test 
current and dynamic resistance are available 
from most catalogs. 

If the extra lead is not objectionable, the 
signal tracer can be left attached to the zener 
during these tests. With practice, good zeners 
can be sorted from bad ones almost by ear 
alone, on the basis of hum and noise. But if 
this has not been done, a final check for noise 
should be carried out. Raucous, splattering 
noise indicates immediate disposal of the 
zener. A fine-textured hiss at low current levels 
is pennissible^ urdess it shows a tendency to 
increase with time or current. Larger zeners 
should be firmly rapped with an insulating rod 
to check for loose internal connections, 

Zeners that have passed all tests might be 
marked with fast-drying modeling paint, in 
resistor color code^ as to their values. The paint 
will also sei*ve to indicate that they have 
passed a fairly comprehensive test, 

. . . W2DXH 



Bibliography 

There is not very much literature available on zener 
diodes. Most of it t^nds to be rather conden^d for engi- 
neering purposes. If you can find some to read, don't 
hurry. The usual engineering training includes lots of math 
and theory, so that the brief accounts cikrry much more 
information than at first meets the eye, Try to find more 
than one of these t 

1, Millman & Taub: Puhey Digitul and Switching Wave- 
forms, McGraw-Hill, 19B5, p. 1S5-189. 

2. Cutler; SemicoriductOT CtTcitit Analysis, McGraw-Hill, 
19B4, p. 564, 

3* Stirina & Herri ck: Setniconductor Electronics* Hnlt, 
Rinehart & Winston, 1964> p. 304-312. 

4, Littauerr Pulse Electronics^ McGraw-Hill, 1965. p* 
120-121. 

Also see: 

Motorola Silicon Zener Dioile and Rectifier Handbook. 

IntematiDnal Hectifier Zener Diode Hnndhnok, 



118 



71 MAGAZiHE 




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PNP silicon epttaxial low leakage 
transistor in TO- 18 package. Similar 
to 2N2185 30 vojts at 150 mw, 

3 $1.00 
Similar to 2N329A general purpose 
PNP epitaxial transistor in TO 5 pack. 
Low leakage 30 volt unit with a 400 
mw dissipation rating and B 30-80. 
Comp. with a $9 value, 4/$1.00 

Similar to 2N3060p a 60 volt silicon 
PNP in TO-46 pack has a B of 30 
with 4 W dissipation. Used in DC 
amplifiers, high voltage work and 
audro systems. 4/$ 1.00 

Similar to 2N1640 bidfrectional trans- 
istor* a TO-5 silicon unit, in which 
the emitter and collector are inter- 
changeable. 40(^ each 

Similar to 2N339'2N34L etc. High 
voltage medium power units. NPN 
silicon. 7/$J*00 

Similar to 2N547A, B and C, etc. TO 5 
NPN Si unit with its own heat sink 
mounting. Picture A. 5 $1.00 

Similar to 2N728. A high frequency 
NPN TO-18 unit extending to the UHF 
range, 5/$l,00 

Similar to 2N545, a 5 watt NPN TO-5 
high voltage unit used for fast switch- 
ing. 5/ $1.00 
Similar to 2N721 PNP TO 18 silicon 
unit, 500 mw drssipation to 80 mc 
frequency. 4 1-00 
Sfmifar to 2N1648 NPN high vottage 
20 watt silicon unit used in power 
output stages and power transistor 
drivers. 2/$l-00 
Similar to 2N2875 PNP silicon 20 
watt power transistor with cut off 
frequency to 30 mc. Picture C. 

2/$ 1,00 
Sfmllar to 2N2885 NPN and TMT8635 
PNP microtransistors. 75 mw power 
at high frequencies- Both units $1.00 
Similar to 2N247 PNP germanium. 
Good for rf work, 10/ $1.00 



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case. 4/$1.00 

Similar to 2N327A PNP silicon TO 5 
unit used in audio. €/$l«00 

Similar to 2N519 silicon PNP unit 
used in rf circuits. 10/$1.00 

Similar to 2N389, 424» etc, 85 watt 
high voltage NPN silicon unit in 
TO-53 case. 75^ each 

Similar to 2N1209, 2N1212, etc, with 
similar electrical characteristics in 
11/16" stud package, 75^ each 

PET'S N channel type similar to 
C610 used as amp. switcht chopper- — 
very high input Z. $1.25 each 



DIODES 




10 watt zeners. 2-70 volts, state 
voltages desired. 50^ each 

1N429 6 volt double anode regulator. 
2 watts, 5/$1.00 

SV176 7 volt reference- 5 $1-00 

SHicon bilateral switch (picture B). 
Replaces two SCR's by firing in 
either direction when breakdown 
voltage exceeded. Used in ftght 
dimmers, etc* 2/$1.00 

Silicon voltage references (Picture D), 
There are a series of precision regu* 
lators designed to operate under ex- 
treme conditions up, simitar to 
SV140, SV3207. etc. 50^ 

1N252 a high frequency silicon diode 
used to 1000 mc. May be used as 
discriminator or detectors. PIV of 20 
volts. 10/$1,00 

S284 similar to 1N252 but with PIV 
of 30 volts. 10/$1.00 

Glass diodes. Color coded. Si 20/$1,00 

Ge 30/$ 1.00 
1N34 In plastic case. General purpose 
germanium diodes. 20/ $1.00 

Microdiodes similar to MD27, etc., up 
to 200 PiV at 30 ^a. These are switch- 
ing diodes with a short recovery time 
(.3 Msec), 6/$1.00 



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TERMS: FOB Cambridge^ Mass Send check or money order^ included 
postage, average wt. per package V^ \%. Affow for COD. Minimum 
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OCTOBER 1966 



119 




I 



fmOO/AM E>ET 
AND OSC 



SPKR 




LOCAL 
INJECT tO« 



AGe 



(Continued from page 4) 

tional components. But iJiese scheniatics look 
\ery odd to a person used to conventional 
tube or transistor cireuits. They seem to con- 
tain an awful lot of transistors. There's a good 
reason for this. Transistors are the cheapest 
IC components to muke— and they take up less 
area than other components. Low-value resis- 
tors (it's dilKcult to make resistors over 50 kO 
with monohthic IC's) are next smallest Ca- 
pacitors take up tlie most area so they are 
most expensive components to make. Since IC 
chips are small, capacitors over 500 pF are 
rare. So far, no one has developed a practical 
way to make IC inductors, so coils have 
tu be outside the IC package. 

These facts have meant that IC designers 
use as many transistors as possible and few 
resistors and capacitors. This is quite different 
from conventional practice, but isn't necessar- 
ily a disadvantage— once you become familiar 
with IC practice. 

Devices using integrated circuits nre usually 
simplest when they use two power supplies, 
one with a positive ground and one with a 
negative groinid* This helps avoid the com- 
plicated bias networks and large decoupling 
capacitors diat would otherwise be necessarj^ 
with so many interdependent transistors. 

Linear or digital? 

In terms of use radier than construction, 
there are two t>pes of integrated ciicuits. 
Digital ICs are the multi^ ibrators, gates, 
eounlers, dividers, and so forlh used in com- 
puters. Most engineering attention up to now 
has been focused on these digital IC*s since 
they can simplify the construction of com- 
puters tremendously. Digital ICs have many 
possible ham uses: keyers (such as the Kindly 
Keyer in the July 73 and the Micro-Ultimatic 
in the Jmie 73* Botli of these keyers use very 
inexpensive Faircbild epoxy-case ICs: $1,50 
and 80p for example.), dividers (as for getting 
1 kHz markers from a 100 kHz crystal stand- 
ard), counters (frequency meters that count 
the number of cycles per second), control cir* 
cults, mixers and detectors. Expect 73 articles 



Fig. 2. Possible integrated circuit receiver of the 
future. The local injection could be a frequency 
synthesizer or conventional oscillator, 

on these topics in not too long. 

Linear IC*s are the other type of integrated 
circuits. They are amplifiers* A simple sis 
meter converter using linear ICs was de- 
scribed by W3HIX in the October 1965 73, 
Until recently^ linear IC*s have been very ex- 
pensive. However, the prices are dropping 
rapidly so we can expert to see more and 
more of them in hi-fi sets, radios and TV's. In 
fact, one RCA TV set al dy uses a single 
Unear IC for its sound if amplifier and GE has 
just announced a linear IC for less than $1.00 
in quantity. 

Linear ICs are used in applications famiUar 
to every ham, imlike digital ones^ so linear 
ICs seem more interesting to most of us. They 
can be used for amplifiers, oscillators^ mixers 
and much more. 

IC*s are of many types. Some are simply 
conventional amplifiers in small paelcages, but 
the most interesting and promising ones are 
quite difTerent* The basic configuration for 
many ICs is the differential pair shown in 
Fig- 1, Tliis circuit was chosen because it*s 
very versatile, uses few liigh-value resistors or 
capacitors^ and has excellent temperatiu'e sta- 
bility since the transistors are matched. Dif- 
ferential amplifiers can be used as oscillators, 
amplifiers from do to VHF^ Unears, fretiiiency 
multiphers, mixers, product detectors, signal 
generators and so forth. They can be used in 
either push-pull or single-ended, and can 
easily be adapted for squelch or gain controls. 

The constant current source shown in Fig. 
I is usually included in the IC. It consists of a 
transistor regulator and a few diodes* Emitter 
followers, cascade ampUfiers and other refine- 
ments are often included in the IC to increase 
gain or input impedance or for other reasons* 
Lots of terminals (10 to 14) are connected to 
\ital points in the circuit so that the IC can be 
used in many ways: ac or dc input or output 
coupling and AGC or squelch terminals, for 
instance. ICs come in small {W x %'') flat 
packages and in cases similar to transistors. 

ICs are made in widely different configura- 
tions, gains and frequency responses. They 
are made for manv uses. Most are consider- 



120 



73 MAGAZINE 



ably more eoniplex than the one shown in 
Fig. 1. A typical linear airiplifier is the RCA 
CA30C)5. With external timed circuits, it can 
give 20 dB of gain at 100 MHz witli +6 volts 
on the collector end and —6 volts on the emit- 
ter end. 

How Will IC*s affect ham radio? 

Ham operators will benefit from the IC's 
that turn up in their commercial equipment 
in a number of ways: increased reliabilit\% 
more features^ better perfomiance, smaller 
size, less weight, lower power consumption— 
and lower prices. It probably won't be long 
before we see IC's in ham equipment made 
by progressive manufacturers. A single IC can 
replace the tubes, transfomiers, resistors and 
capacitors associated with them in a conven- 
tional // amplifier; Selectivity in modem 
equipment is generally provided by crystal or 
mechanical filters^ but tlie spurious responses 
that Sfmietimes pop up in odd places with 
naiTow-band filters could be a problem. 
Nevertheless, tliey can be taken care of. In 
fact, the tremendous cheap gain available 
with IC*s means that resistor-capacitor shaping 
and feedback networks can provide consider- 
able selectivity, even at 455 kHz or higher. 

IC detectors and audio amplifiers also 
should become popular in not too long. It'll 
probably be a bit longer before IC's are used 
in rf stages. They can*t reduce the size of front 
ends too much, but they do have some fea- 
tures to offer. The low noise, high gain and 
high input impedance of IC*s means that de- 
signers can build fairly high selectivity into 
the tmied circuits before the first rf amplifier. 
IC's can also give exceptional AGC without 
complicated external circuitry. 

The ham builder will find that integrated 
circuits hardlv end his fun. Most IC's now 
available are building blocks, not complete 
units. They can be put together in many ways. 
Soon IC's will be very cheap. They're already 
easy to wire up. In not too long we'U be able 
to use more complex (and desirable) circuitry 
than weVe tried in the past, yet still have 
inexpensive and easy-to-build equipment* We 
have plenty of building to do before we all 
become operators (or TV watchers) instead of 
experimenters and builders. 

The future of integrated circuits is very 
bright p They have plenty to offer aU of us. 
Learn a little about them now so you won't 
be lost as they become more popular. Dont 
stand in the corner with your back to every- 
one crying "Tubes forever!'* (or even **tran- 
sistors forever!") until you've been passed by. 

, . , WAICCH 



Interested in VHF? 

Then why not send for a free sampte of the 
VHF'er Magazine. It's devoted entirely to 
serious VHF and UHF hamming^ It contains 
articles by well-known and capable VHF'ers- 
All who want to Improve their knowledge of 
VHF are invited to subscribe. 

Subscriptions are $2 a year (foreign $3) 

The VHPer 

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Modulation reports: "Excellent," ^'Recognized Twoer 
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LIN-AMP PSl. $34.50. 

ABSORPTION UHF WAVEMETERS 

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I 



OCTOBER 1966 



12T 



JACKSON MODEL 652 Audio osciflator 

20 to 20000 CPS Good condition $37.50 

APW II Covity — ^2800 to 3100 MC 

less tube $ 

With 2C40 tube ..,..,.,. 

Complete APW transceiver less all 

4-400 Chimney SK 406 .*--.. 

255A Polar reloy - - , , 
2 55 A Pol or reloy socket 
GH ] 203-2 Transformer 



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We'll pay you the absolutely Highest Prices for almost 
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SURPLUS WANTED 





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ic For ¥T extra we can maintain o reply boic for you. 

ic We cannot check into each advertiser, so Caveot 
Emptor . « . 



ALL MAKES of new and used amateur equipment* 
Write or call Bob Grimes, 89 Aspen Road, Swampscott, 
Mass. Tel : 617-558-9700 ot 617-598-2530. 



GONVERTEKS- World's largest selection of frequencies. 
Ham TV vidieon cameras and parts at low factory- direct 
prices. See them all now in our full page ad in thlg 
b&ue. Vanguard Labs» 196-23 Jamaica Ave,, Hollis, H Y, 
11423. 



WE WILL PAY CASH: Wanted, popular, late mode! 
unmodirted amateur eauipment. Highest prices paid for 
clean f good operating gear. Write Graham Radio« Dept, 

10, Reaclinff, Massachusetts* 



ARE YOU SINCERE? Are you really looking for the 

best deal on ft new or fully guaranteed used unit? Let 
us convince you with a specific quote that will reolly 
save you money* Graham Radio, Dept. 10, Heading, 
Massachusetts. 



BUILD WlJJL's popular CPO-CWM (code practice 
oscillator-CW monitor) from the July 1965 73. page Z2. 
The predrilled board with component locations flilk- 
screened on it is only 50^. The board with all parts 
mounted on the board is SB and the unit asBembled in 
an attractive case is a remarkable $7,95* Order today 
from the Harris Co., B6 E, Main St, Tornngton^ Conn. 

25 WORDS FOR S2. Sell or buy through these want ads. 
a terrific bargain. Caveat Emptor, 73 Magazine, Peter- 
borough. N* H. 03458, 

NOVICE AND TECHNICLAN HANDBOOK by W6SAI 

and W6TKS. Limited quantity for only $2.&0 each. 73 
Magazine, Peterborough, N* H, 03458. 

B & 2 HAM CLUB will hold its 5th annual banquet at 
the Moran and Galvin Restauraat, Hillside, IlUnok on 
OcL 8. Cocktails and Hors d'oeuvres wiU be served at 
7 pm, dinner at 8. Tickets $4.25 from W9RHZ, 968-5746, 

FREE 20 WORD elasiiified ad with year*s subscription to 
Ham's Market Newspaper. 12 big issues only $2.00, or 
aend QSL or post card for sample copy. Box 13934, 
Atlanta. Georgia. 

SPAULDING SPECIAL tiltKJ^er ham tower, HDTX, 54 
ft. 4'*'* and 5" vertical support pipes, also antenna drive 
pipe, 1 V4" included* Never used or assembled. $100. 00< 
Steuben J. n:ure. WgDQW, 2099 W. Slst St., Cleveland, 
Ohio 44102. 



122 



73 MAGAZINE 



RTTY GEAR for sale. List issued inontbly- 88 or 44 mhy 
toroids five for S1.75 postpaid, Elliot Buchanan, W6VPC, 
1067 Mandana Blvd., Oaklana, CaL 946 10. 



MOTOROLA new miniature seven tube 455 kc if am- 
plifier discrimiTiator with circuit diagram. Complete at 
52,50 each plus postage S0# each unit. R and R Elec- 
tronics. 1053 South Yeliowsprlnirsp Springfield, Ohio. 



HERE'S THE CHEAPEST way to DXCC, WAZ, WTW. 
TELREX TM:MJD wide spaced Triband Beam new March 
1966 Serial 35012 ; yours for $225.00. Bandit 2000A con- 
verted to 2000B, Serial 439 hae fouT new 572BV— $215,00, 
HEATH SB— 300 Receiver with CW Filter mint condi- 
tion 1175.00. K4ZJF Milt de Reyna 4030 Hallmark Drive 
Pensacola. Fla, Phone Area 904 4S3-65d2, 



WRL'S BLUEBOOK saves you money! These prices with- 
out trades: Thor & AC— $323,10 ; KWMl— $224.10 ; III/ 
6m— S125,95: HT40— »4ft.S0 : SX99— $85.05 : Apache — 
1116.10: HXIO— $260.10; SR46— $134.10 ; HQ170C— 
$18g-10; Kingr 500C— $233.10 ; 2A— $161.10; Ranger I— 
$89.05. HundTeds more, free list. WEL. Box 919, Council 
Bluffs, Iowa 51501. 



POPULAR RT-40 TRANSMITTER- 75 watts. SO through 
6 meters, AM/CW. Good novice or standby rig. $40 FOB. 
WASLTC, RFD 3, Box 8SA, DeniBon, Texas 75020* 

HT33A — Formerly Ted Kenry*s. Modified by Bob Adams 
(He designed the 2-K i with vacuum variable and two 
additional VR tubes in screen supply. PL- 172 excellent. 
First check for $240 takes — will split shipping or deliver 
LA area. 

Also near new TA-36> Mosely 6 element tribander — $90. 
K6UJW Joe Fischer, 4B25 Regalo, Woodland Hills, Calif. 
91364. Telephone Eves 213-340-3601, 

WANTED: Military. Commercial, SURPLUS . • . Air- 
borne, Ground, Tranamitterg Receivers, Testsets, Acces- 
sories. Especially Co U in a. We Pay Freight and Cash. 
RITCO ELECTRONICS Box 156, Annandale, Virginia 
(703) 560-5480 COLLECT. 



BUILD A CODETYPER, TransiBtoriaed electronic com- 
puter-typewriter for Morse teaching or keying your rig 
with fb fist. For schematic, parts list and technical dope 
send $2 to Computrontcs Engineering Box 6606 Metro- 
politan Station Los Angeles 90056. 



ATTENTION BEGINNERS— Complete sUtion Lafayette 
KT-320 w/spkr— Adventurer w /modulator and mike, in 
excellent condition— $70. WA2VWG, 6029 56 Drive, Mas- 
peth. K.y. 11378 

HILLSBOROUGH AMATEUR RADIO SOCIETY 
<HARS)- Annual Tampa, Florida, Hamfest, October 16, 
1966, Rowlette Park, Hillsborough River & 22nd St. Free 
Parking & Lunch, Lots of Prizes* 



THINK FI^ZZY! Unusual new comedy record, Intellec- 
tuai slapstick. Side I "Computer, Go Home!") is wild 
science fiction. Side 2 is **The N&ked Interview." Spoken- 
word 12'* mono LP titled THINK FUZZY! postpaid, 
$3.98 (Va. z'^idents add Z% sales tax), from "Dogbite 
Record Co., Dept 73A. 2040 N. 16 Street, Arlington, 
Virginia 2220L" 



NOTICE CRYSTALS 8O-40M $1.05 each. Also other 
fre<i^. Free list. Nat Stinnette W4AYYp Umatilla, Fla. 
327B4. 



TRANSCEIVE! Best offer or $225.00 check takes 6 
month old Eico "B*A transceiver with Bolid state VFO and 
751 AC power supply, shipping prepaid with advance 
payment. Dr. W- A. Farone, W4CYP. Et. 1 Box 283X 
Conduit Road, Colonial Heights, Virginia 23S34. 

OCTOBER 1966 



TransTomef pri. llTi 60 <a^. Tapped sec. 1^00? C-T.® 200 
ma. and 7 40 C:T @ 235 Ma. 3200f test. Wt. 12 Ih. $3.25. 
Sealed. Mtfi. scrt-s's. SUnd-olI itnns, 

TrfiHEforiner pit 105, 115 k 125t 60 c?c. Sec. ^*>^J ,^'J- if 
250 ma. Sealed case. Ml*, screwa. Stand-oil terms. Wt.S lD.*-i.ou. 

Isolfltlon iranfrformer. 115f 60 crc pri. Sec 1I5T. 50 vatt. 
Open frame. Mtg. holes, Wt. 31b. fLZ5. 

1 KW, Variable ladiietof. Jobnwii 226-5. Stipfi- Wt. 10 lb. A 
rare bii^ain at $25.00. 

5 mfd. at £000 Toltt fledrDlytic. Mtg. bracket. Wt, S lb. 
11.25 ea. 

3.7 to 52 mmfd. firtatole cap. HF-SO. Single hole panel mount. 
60i* ea, or 2/11.00. 

AH items «• ntw and F.O^B- Worthington, Otifo 

fl.RX. Safes. P.O. Box 12, Worthington, Ohio 43085 



LAMBDA REGUUTEB POWER SUPPLIES 

Model C281M 125-325 Volts at 200 Mills $30.00 

C481M 125 325 Volts at 400 Mills $40,00 

C881M 125*325 Voits at 800 Mills $60.00 

C1581M 125-325 Volts at 1.5 Amp. $9900 

RAYTHEON Voltage Regulator Model VR6116 

95435 Input 115 Output at 250 Watts Special $15.00 

All equipment in Excellent Condition 
Mass. Res, add 3% Sales Tax 

ELI HEFFRON AND SONS, INC. 

321-329 Elm Sl-reef- 
Cambridge^ Moss. 547-4005 



NOT NUTS — CRAZY 

CRYSTAL Uri^KIt Sli r I LTKR— 4990,00 eenter fr&q. Bdb band 
PiiHs 4,9^0400 to 4.UlJ:i250 MC; stop band at —^^db, 4.985 
to 4.9800 MC. Input il 3000 ohin, baUnoed; output Z 680 
oh!ii, tmhiil«iu'i?ri. Inw^rtlon loss 2% db max. Made by BLALK- 
HAWK, for lIKATU's Marauder. BRAND NEW $6.00 
AIB DUX— 3'' dia. 3Vj" long; 12^ tuma, tapped at 1^/^. 
3V] Vnd 0% lufiis, for EliATW^ WAEBIOB. BRAND 
NEW $l*a5, 4y$4.50 

AIR MUX— 1%^' dlii, 3%" lone: 37 turns tapped *t ^, 8. 
la. and 20 lurns. For HEATirs DX-20. NE\\ 69^ ea., 4/|2.6D 
LINK— ly." dJa. r long; 6 turns, CT, w/pMe choke. 2 | 6 
nn-U^j- link" lor HEATH^i Seneca, NEW 50^ «a., 6/$2.75 

HEATH'S CABINETS 

AH modern design, BRAND NEW, less ftwi panels. 
hm UX-IOOB— 19%** wid€, 10%*' high, 15" deep, t^ 
sitiudiird 19" X 10%^ paiicl. Copptr plated, lid in top. ^l^ou 
Si-jNETA— 16^" uide, 914" blgb. 10" top. Takes IG" x 

;»'' panel, Copper plated, Ldd in top. $6.50 
1314" wide. ^%'* high, 1** deep. Performted. 2* bole in one 

lie. No iid, not plitl**4 $2,00 
See Moy 1966 od, in 73, for olhef HEATH cobinets ovaSlable. 

HEAT DISSIPATING TUBE SHIELDS, 

and plate caps 

SHlO,n?^^for 7 pin 1^-. 2 A^ 2^" tall; te S pin 1%, 2 
k 2^^" tilL 290, 4/$iaO 



SHTKU*— lEKC #T*12. bw, S'* sq. 1%" hlgb, hmtt 1%" 
dia, 2%" high, for "G" sTzc tube, 2%" to 4%" talL Fits 
6146, 5B4GV. 5^33, etc, $1.25 «l., 4/$430 
rArs^alumitium, flt 6146^ 807, 1625, ete„ less ^t smws 23ft 
5/51,00 

HAMFEST SCHEDULE 

Sprine Milts Stole Park, Mitchell, Indtpno Oct. 16, 1966 

Ail unltTsr, exa^pt In emeri^fif?, or I'm at a hamfest, shipped 
*iHmp day n'eelf*fd. For fret "iJiHlUIlT' sheet, send self -addressed, 
.sL.ioii>ed envelope— PLEASE, FLE.iSE iDthide sufficient for postage, 
aoF etcesa rflurned with order. I carry prlTate (Trafeler^j 
parrel post insurance, for domestic pare* I; post. For Items ti 
[ira^vy; or ti>o larie for pareel post, I sygfest bus parcel e^i'" 
nvi^ advi» mme of bus lirje, and city* where you eau pn^a 
up the ^pueiit. 



B C Electronics 



2333 S. 



Telephone 312 CAIumet 5-2235 
Michigan Avenue Chicago, flfinols 60616 



PRICE BREAKTHROUGH ON BEAMS 

FULL SIZE; new eompMe with boom and hardware; SWH 
1:1; haniUt^ 5 KW; adjt^table entire band; %** and 1" 
alum, aliof lubltig; single coaxLU feedline: 

3 El 20 ii *<■•• 22,.'*^ 6 El 10 . . . * • • , , * * ■ 2o,'^ 

2 El 20 - , . . 16. 4 El 10 .,...-..;.. IS. 

5 El 15 , , 28.* 10 El 6 . . , , 32.* 

4 El 15 . 4 • « * 4 4 . « . , , 25^* 4 El 6 » , , . 15. 

3 El 15 .,,. 16. *Has 20' steel boom 

ALL BAND VERTICAL V80 (« Ihrii 8U) ?X6.95 

ALL BAND VERTICAL V160 ii\ thru Hit)) _ 18.95 

QUADS: PROVEN SENSATIONAL! All metal (except sp:icing 
instilatar (iiiwt^s); fuH size; Hu tktmnt; jibsolutely eomiilete 
v^itb Htei'I limm; all bardwart^: wire und firtiii^; terrific gain 
;mcl directivity; one man UistalhiUDn: no iiamliuo or fltiregbiss: 
all quads uije single 52 ohm c^asliil f-'-dlint*: 10- 1 5-20 Quad, 
>5; 15-2a Quad, $32; 10^15 QimiL SiiO; 20 Meter Quad. 
$25; 15 Bleler Quad, 52 i. Remit with ordt>r, sliijjped charge 
collect* 

GOTHAM, 1805 Purdy Ave,, Dept. 73. Miamf Beach. Fla, 33139 



STOPf LOOK!! READ!!! 

$1,00 wilt ffome & display 60 QSL 
Cards in 3 of our 20 compartment 
plastic holders, or $3.00 gets 10 hold- 
ers for 200 Cords* Order now — elimi- 
nate rhe mutilation & headaches of the 
obsolete methods, & have a neot, at- 
tractive shack instonlly. Prepaid & 
guaranteed. 

Free sample avoHable to Dealers, 

t€palic«, Bqx iS&Mr GallDUn, Tenn, 37066 




PLATE TRANSFORMERS— $39.95 

36000-3600 VAG @ lOOQ Ma., CCS, with 120/240 VAC 60 

cps primary. Commercial quality units maniif^iclyred by Wagner 
Electric Co. meaiure 13'' ttlgh. 12'' wide, arrd 9'' deif* Ntt 
weight h gSi:. PTit« $39.93 F.O.B. MinfieafioEis. 0iif year 
miconilitionaJ money back siarant&e. Terms: Check ar MM, with 
order, ImmeUUtc delivery. Write or Phone: 



PETER W. DAHL CO. 

3314 Dmmoiiil Prlv« 



El PflsOp T4^xas 



RT220 'ARIi2l TMXS Transceivm 9112-1213 tnc ..EX 145.00 
1H129B/A9H9 Tuning CniL 2^*00-4 1 riOmc. W/Tuties LS 29.75 
10226A/APft9 Panonimic Indlcilor. W/Kcliematlc .,K\ IU.50 
AN/APN86 .\(itpnna. Hoeing Purl Nr>, 4-2146-2 ..,.NKW 3,75 

UPM4A i^f^iK IIV aiid Filainent Transfomier NEIV 4.T5 

UPMllA M'V Viilt w/g Tiibf^ md Wiring Diagram ,NEW 4.50 
R316A/ARR26 H-TuIm! AM/FM SurHThet. 162-174 mc IM 22.75 
C610 Gontrot 8ost for R^lfiA lEmlvw, W/4 Tnbt« _EX 4.50 
ID169C/APN12 Sfor^e. 3JP1 CRTJ»PDT €mx Switch LN 12.75 
3JP1 CRT vi/MoMiil, Slildd, Snckrl, Iiilensifler Plug .. 0.25 
Crax Switch. Wm. Thomiison PniEhirLs No. ElgB22{!A LN 2.75 
BV RcctifiiT CartritlD^S. Ttvd ^f/MfrtlOV, I5miL MminU^fl TiN :i,lK) 
RT82/APX6 (uiikvK 1215 ma Xil\^\xvT. Stie Oct-Kov CQ NBW 23.50 
UPM8 Trnls APXti. 27 Tubes, 10 Dlaik^s. llSVtiOcy LN 111.75 
Complete Mam^l for TS72lVUl*M8. PiMpatd ../....,, 2.&0 
T61A/AXT2 TV Xmir w/Vlrico & Sync MrMiwIators .NHW 19/i5 
TS545 Ech« Box. nr>0-1350n!C lODua ludieaiur ..NEW (1.75 

Complete Mantial fur T8ii45/IT. Postpaid N'KW i MQ 

OAA-2 T«l Sit. 150-2 iLlmc. SOOun Ind. llSCfiOcy NEW ».50 

Schematic for iiAA'2 T^si 4^tt. Postpaid ,*..... 1 .00 

46ACa Ki Tub' ^'niM^rhet. 175-226nn!. wo/Fowcr Supply 22.50 
Schimatle fnr Q Ueeeiver, isllons Power Supply .... l.ftO 



Ali665AyAaS2 ITidK Band Pass Filler Mnpllfier 

AM818A AaS2 S-Tiibe Dual Chmime! Amptifkr 

Ballentine 300 AC \TOi in 19 inch Eadi Panfl ,. 
Rcllectoin«t«r SWE Bridge w/Meter. 30-lOOOmc . , . 
AS313B/ARN6 Su^tiDD Seeking Loop, 100-lT50kc . 
Set of 120 Xtals Type FT24a 5fi75 thnt S650ke . . 
C22A or C984 i^mitrol for R13A ARC Ti^pe 12 Rec . 
G45 rmitnil K(>k for ARCl aiid AKC12 XceUers ,., 
C45 Rjimo i\^Tfiit iised, cxcelJtnt , . * - , > *.,...*. 
Precise HV Probo 5(10 niegyhm, HOKV InsulaLiou . 

Varlstor, J4V. BlrmiilM^rg-Onrlsoij Bfi7201-Ull NEW 

Rt. Antil^ Drive. W/UniversaL 14" ^mft ..EX 1.75 ea. 



6161 Typ« Tube. WV Con nee tors. 015 Walts to SOOOntc .EX 7.50 
2-50. Uhiiillt! RF Clioke, 7uli ,•.,.•...*_»,.. EX 8/1*00 



Pilose incEude your zip ccnJe wheniivcrr 
ycm write 73 obout dnything. 



/NE\I' e.25 

NEW 5.50 

KX 27.50 

. .EK 9.75 

. ^EX 4.75 

12U/li?.75 

.NEW K75 

.NEW 1.25 

.NEW 2.5 If 

n/]An\ 
3/5.00 



E C H AYDFKI ^**^ ""*- ^*^y s<"'"^ Louis, 

E^. W. n« I MCI^ Mississippi, 39520 

Pnces: FOB Bay Samt Louis. Terms: Net, Cosh, 



HEATH VHF-1 with spare power transformer $140.00, 
Eico #7:^9 Ail Mufhilal«>r (for VHF^l) with cover J45.00, 
Haramerlund HQ-140X receiver $120.00, Atneeo 6M nu- 
vistor converter with power supply $3S.O0, Ameco 2M 
Nu viator pre-amp $7.00, L&W 61 2 Mtr. tube converter 
$10.00, I^f&yette HE-45B I6S.00* HI-FAR halo and 
bumper mount and alNcables and connectors $10,00. 
Everything: in excellent condition both electrical and me- 
chsnieaL Will pay all shippingr charges, Eiebard Depweg 
WQIQU Box 186, Scott&hurE, Indiana 47170 

TECHNICAL MANUALS— $3.00 each BC-1031, ARN-6, 
ARC-27. Schematics for ARC-1, R^88, TS-497A $L00 
each. Many others, list 10^. S, Consalvo, WSIHD. 4905 
Roanne Drive, Washinfifton, DC 20021. 

WANTED Goldkit Thriller or EI.31 DX rig box 1225, 
Jacksonville, Florida* 

MLLTI-ELMAC AF-68 TX 80-6M with \M070 F.S., 
12VDC Dow relay & mobile mounting bracket ; excellent 
condition^ $110— KlZDl 174 Andover Ed. Billerica, Mass, 

TO 18 FIELD EFFECT TRANSISTORS $LOSp resistors, 
capaeitura, translstorB, diodes and many other bargain 
packs Bend for list to: Solid State Fax* P.O. Box 20G, 
Dorchei^ter, Mass, 02124 



< 



EXCESS GEAR AND PARTS, Vac, Yariables, Variable 
coila, tubest metera, transformers, 2k w linear, diodes 
VHV), etc. Stamp for comidete listj "^'GMCS, Rt 1, Bas 
666, Arroyo Grandej Calif, 

ESTATE SALE and bargain list. Send for it and include 
SSAE. Write Paradd Sales and Engineering Service 280 
Route 10, Dover, NJ- 0780L 

RTTY (;EAR for SALE. List issued mnntbly. 88 or 44 
Mhy toroida five for $1.75 postpaid. Elliott Buchanan, 
WOVPC, 1067 Mandana Blvd. Oakland, Calif. 94610. 



C. FRITZ QSL'S — World famous, and of highest quality 
consistently for over 30 years I Samples 25^ (deductible) 
Box 1(jH4, Scottsdale, Arixona 85252 (formerly Joliet, 
UH noU) 

SWAN S50 8117 AX AC/ PS $370; Gun^et Comm III 2M 
$1:^0: Lincoln 6JhI XCVE $15. AH units in top condition, 
first certified check tekes any or alL L. B rower WAS- 
DAV, U040 Cherry Ave.^ Morton Grove* IlL 

^ i^ ^ — ^^ 

"LOUISVILLE KENVENTION, Oct. 15, Kentucky Fair 
and Exp<isition Center* All under rooft grand banquet, 
technical forum, giant indoor trade-o-rama (bring your 
goodies) p booth exhibits, C. W, conteat, Homebrew eon- 
test New, different. Registration $2*00 at door. First- 
claes women's prog; mm and luncheon reciuires advance 
registration $3.00. Deadline Oct. 8, P.O. Box 2OO04, 
Louii^ville, Ky. 40220." 

TWT: New; 1000 to 2000 mc : 8 DB notee figure; 35 DB 
gain ; all specs. Offer or trade? Finger, Box 10, AFO 
San Francisco, 9«>34:i. 



COLLINS 75S-1 receiver. In perfect condition, complete 
with operating manual $239*95. Local pick-Up only. Clay 
Welsh WB2SCD/1, 56 Baldwin St., Springfield, Mass- 
Tei 7SIJ-7604. 

LOOK! RECEIVER BARGAIN! NC-SOO in good condi- 
tion with matching .speaker and calibrator— Ask $120. 
WN2VPSi 4 Wir.linf? Rd., N. Ma&aapi*tiua^ N.Y, 



MUST HELL! All jioud tnridition, Elmac AF*i8 & M1070 
P/S $00.00; Guiiset Comm 3, 6 mtr. $85,00; Heath 
Shawnee 6 mtr, $100.00: TE*20 Signal Generator $20,00, 
New DC supply for TR-:i, $100.00 Heath 2er. dc supply 
& halo, $49,00. Bert 0, Jones K5FVH, UOe North MIsb, 
SL, AmariUot Texas 71*106 



124 



71 MAGAZINE 



CLEAN VIKING 2. $05. With VF-l VFO, $70, 46 states 
worked as novice, 200 watts AM/CW- FOB WA0NDV, 
eil North Hartup, McPherson. Kansas, 67460 



MUST SELL WA2YQW to amateur radio^ makes ^ood 
Hudson Dtvkioii Director, Hamster Radio Club, 1129 
Astor Ave., Bronx, N-Y, 104€d 



BARGAINS: GSB-lOO gl69.95; HW.I2 $99.00; 32V2 
$99.00: HQ-XTOA Sl89,95; SB-34 (NEWJ $349.00; HQ-llO 
$119.00: Cbiillenger $49,00; HG-10 $19.99; Write Elec* 
tronic Sales, Box 2225S, Memphis, Teiiii. 38122 

WANTED; OSCa/U Oscilloscope in new or like new 
condition, send bids to Charles E. Helsler K3VDB, 116 
Dixie Drive, Bed Lion, Pa, 1735$ 



BRITISH EL 37 DX transmitter write A, T, Cllne, Jr., 
240 Peach tree St, KE Atlanta, Georgiar 80303 

SX88 — $275, Is in very good condition. D- C, Shotiltz, 
301 Humewick Way, SuTinjrv^ale, California. 

SBIO HEATH KIT SSB Adapter with cables and manuaL 
Mint candiiian, ?60,00; B. Doktor* KIJNT Liberty St,. 
Wairreaj Mass* 01083 

LAFAYETTE'STARFLITE XMTR KT-390, version of the 
famous DX-60. In excellent condition, makes a fine Nov- 
ice rig, $40,00, Also a BC-611 walkie-talkie, best offer. 
Selling for college tuition. Ship REA, Box 57, 73 Maga- 
^ne, Feterborough, N.H. 03458 

QSL CARDS? ? f "America's Finest/' Sample 25^ 
Sakkers, WSDBD FRINT, Holland, Michigan- (mention 

SB2DCP MOBILB POWER SUPPLY for SB-SS trans- 
ceiver* Excellent condition, with manual, $50,00 J, Bur- 
nettp Rt 2*1 Box 1511-F, Panama City, Florida 

NEW SB-34 with Mic $345— Heathkit Q Multiplier and 
Transcom Squelch Mod S-309 both for $fi, W6BLZ, 52S 
CoMma, La Jolla, Calif. 92037 

HALLH:RAFTERS SX-TI and speaker like new condi- 
tion S85Jjn. Heath DX-35, VP-1 mint $35,00. $110.00 
takes all. K, Egbert K2IVJ, 33 Earl BU Denville, N.J. 

DRAKE TR-3 AND POWER SUPFLT, $450 collect. Also 
Heathkit Q-Multiplier, Globe Chief Deluxe with modula- 
tor. Globe V-10 VFO, National NC'173. WA0KKA, 1680 
Kalmia, Boulder, Colorado, 



TRADE COLLINS 75S3, 32S3, 62S1. 516F2 and Johnson 
6N2 for Leica M3 or locksmith suppli^ or 16 MM movie 
outfit, give or take difference, What*s your offer? James 
F. Bingham KTIMH, P.O. Box 516, Beaverton, Oregon. 

GALAXT V with AC and DC supplies^ AH In original 
cartons and like new condition* $435 takes everything 
including mobile bracket and Turner miciophone. Victor 
Huvelle, K5MJF, P. O- Box 66282, Houston, Texas. 



TUBES WHOLESALE! Factory fresh, prime quality; 
65 to 70% of? list. Year guarantee all types transmitting 
& receiving ; newest & obsolete. Send 10^ for info. Jul 
Hoist man, WA9AVV. 506 Putnam St, Ft Wayne, Ind. 

4(>808. 

GALAXY y, AG and DC supplies, speaker console, 
cables. Hustler antenna, 75-40-20-lB resonators, and 
mobile and desk FTT microphones, $510 . ^ . DX-60 
$55, HG-10 VFO $20. HM-15 $10. Numecron call-ident- 
tymeter $13* Cushcraft 5 element 6 meter beam $10, 
AR-22 rotator $22, Paul Gough, 18 Eliot Avenue, West 
Newton, Massachusetts 02166. 

TRANSISTOR CONVERTERS Low noise, crystal con- 
trolled, wired and tested printed circuit- 50-54 mc input, 
14-18 me outputs $15 ppd^ SynteJex, 39 Lucille, Dunaont, 
N. J. 0T628. 



OCTOBER If 6^ 



OUR catHJ^ate for the p<:rfec^t scf^pe. the Duntont 336 A. The 
answ«r to high e^ist ■nits. Mtdliin pirEistenct tnbt, Mnidt band, 
X and Y JunpliRers* foN CDRtrols^ camrra bazel. blower, 37 tubes. 
100 fianos^eDnd em. tract* widely desired by electronU ^hop& and 
industry. Used antil retefitly In a missfj« industry. Now yon can 

save dolfari at only . . , ,....,.-,-•»., , . 5139-00 

famous: DHmofit 304 A Hopt. U^ed In spict Industry. Vertical 
0ain 23 mJMtVdtts per ineh. rise tfmt 2 mrcroseeands or le^. 
works to DC, sweep freq 2 cps to 30 kc. 20 tubes, size I3i9xl9, 
weight 30 lbs. This is a modern all pyrposc scope which may be 
used Fn any shop or industry for general electron It work. $84.30 
NEVER ofTered anywhere hit here! IF-Aidto strip from ARC*21. 
Provides AVC. AOC, AHL. squelth, 3 stagers of aydio, BFO, 3 
^eleetivities, 2 mechanicaf filters, 3 IF Ireqaencies Unpiit I8D0 
kc.. 300 kt. and 105 fcc). Just add a front end and the 16 
latins in th< strip wjH do the rest. Makes a goot} fixed fre* 
quiincy reeeJYer for any network* IHARS. Unicom* 08, AM or SSB« 
etc. Conversion information free. A real value at ,.,.., S12.5Q 
SP-600 RECEIVERS, general purpose, 540 kc. to 54 mc, %%- 
eellt^nt on SSB. CW and AM. %M selectivity, S meter. 20 tubes, 
very low drift. Comnare our price with others. ...... $325,95 

Send stamped addrrssnd ([nvniope for list 

THE R a C WILSON COMPANY 

Box 393, Littleton, Colo. 80120 



CQ de W2KUW 

S% BONUS!! 

Paid over ony fop offer for any piece of aircraft or 
ground ladio units, also fesf equipments, AU types of 
tubes. Particularly looking for 4-2 SO » 4-400 • 033 A 

• 304TL • 4-1000A • 4CX5O00A et oL 17L • SIX 

• 390A • ARM * <SRM • GRC • UPM • URM • USM 
units, 

TED DAMES CO. • 310 Hickory St., Arlington, HJ, 



ARNOLD'S ENGRAVING 



ARNOLD 



WA2ZHA 

AMATEUR RADIO CLUB 



BLACK WITH WHITE LETTERS, VA x 3i/d" 

AMATEUR CALL PINS $1.25 

ARNOLD LIHZNER 

2041 LINDEN ST, RIDGEWOOD, N.Y. 11227 



NAME YOUR PRICEl 

COLUMBIA wants — needs — and MUST 
BUY equfpnnent — NOW! If your gear ts 
in reasonable condition — name the price 
you want for it — and it's a dealt Tell 
us the best price you were offered - — and 
we'll TOP IT! We urgently need: ground 
end oir communication equip., teletype, 
GRC, PRC, ARC, ARN, and Test Equrp, 
If you write us this week — we'll even 
poy freight! Nobody otit'deols Columbia* 

SPECrAL OF THE MONTH! 
COMMAND RECEIVER! 

3^6 Mc, 

Excellent condition* 

Like New. Only 

COLUMBIA ELECTRONICS, Depf 5 

436S West Pico Blvd. 
Los Angeles, Calif. 90019 











Colliiia 32V1 


$129 


Globe 40ftD 


$199 


Collins KWSn 


275 


OlohP LA-1 


45 


CK-JOH and 45S\Ta 


85 


ftlobe DSB 100 kit 


45 


Drake TE:i aiJd AC3 


493 


IJoiii^t G-f T 


59 


Hrake SB 


1S9 


^X-09 


65 


lirakii 2m 


25 


HT-40 


45 



Write for Used Eifii!iT>iiieiit List 

FR£CK BADIQ Ai4D SUPPLY CO., INC. 

38-40 Biltmare An, As\milU, N.C. 2SS01 

T- T, Fl^k W4WL \\\ F. Bedk KiaOK 



MASTER ORDER BLANK 



Name 



Call .. 



* m *-*<* w*m 4 ■ 






City _ State 



****** •■■««' 



Subscription to 73: D 1 year $4 D 2 years $7 

New n Renewal D 



Zip or Country 

□ 3 years $10 
Extension □ 



«•#«'» • 



D Life $50 



n VHF Antenna Handbook $2 
n Parametric Amplifiers $2 
□ ATV Antho[ogy $3 

n CW 504 

Q Core ond Feeding of Horn Clubs $1 

n Horn RTTY $2 

n Receivers $2 



□ Surpfus TV Schemotics $1 

Q Revised Index to Surplus $1.50 

□ Simpiified Math 50<^ 

□ Test Equipment 50^ 

□ Binders $3 per year: 60-61, 62, 63, 64, 65, 66 
n 1963 Bound Votymes §15 

□ Back Issues: O, N, D 1960 are $1 



F 1961 through present are 50^ 

Frequency Measuring, Colli opd Haiii TV are out of print, 
Subscriptioiis take six to eight weeks to process. 



73 Magazine 



Peterborough, N.H. 03458 



INDEX 



Alco Electronics, 106 
Aiqert Soles Co., 96 
AlJJcd Radio, Inc., 49, 91 
Amateur Electronic 
Supply, 64-6S 

American Crystal Co., 104 
Amrad Electric Co., 105 
Antenna Mart, 99 
ARC Sales, 123 
Arnold's Engroving, 125 
^rr^w Soles-Chicago, 122 
ATV Research, 100 
L, L Bobcock Co., 41 
BC Electronics, 121 
Budwig Mfg. Co., iOS 
Coflbook Magazine, 94 
Columbia Electronics, 121 
CtKh Croft, 102 
Davco, Bi 

Peter W. Dohl Co., T24 
Ted Dames Co,, 125 
Devices, 96 

Dow Key Co., Inc., 97 
DRC Kits, 105 
Editors ond Engineers, 55 
Edwards Electronics, 76-77 
EICO Elect Instr, 
Co*, Cover II 

Electronic House, T04 
Epsilon Records, 106 
Evdns Radio^ 102 
Evonsville Am. Radio 
Sup., 121 

EZ Mobile Ant. Mount, 104 

Fair Rodro Soks, 122 

Freck Radio. 125 

Gift Shop, 106 

Herbert W. Gordon Co., 71 

GoHsom, 124 

Grov^ Elect Supply, 101 

Harris Co., 91 



ADVERTISERS 



£. C. Hoyden Co., 124 
Efi Heffron and Sons, 123 
Henry Rodio, 85 
Hoisington Reseorch, 12t 
Hy-6ain Electronics, 9 
International Crystal Co., 3 
JAN Crystals, 121 
Liberty Electronics, 106 
Master Mobile Mounts, 59 
Mazer Enterprises, 121 
Midway Antenna, 122 
Military Electronics, 122 
Mission Ham Supplies, 69 
Mosley Electronics, 63 
Newtronics Corp., 56-57 
Porametric Amplifiers, 100 
Parks Electronics, 104 
Poly Paks, 107 
Quement Electronics, 

81, 91 
Rohn Mfg. Co,, 95 
Sanders Associates. Inc*. 

128 
Sideband Engineers, 13 
Solid State Sales. 119 
Swan Engineering, 36^37 
TAB, 127 

Tel rex Labs, 80^ 84 
Tepabco, 124 
Transistors Unlimited, 103 
Translob, Inc, 99 
Tri-Ex Tower Corp,, 83 
Tristao Tower Co,, 99 
Unadilla Rodiotton, 105 
Vanquard Labs, 45, 61 
VHF'ef, 121 
Woters Mfg. Co,, 5 
Webster, 27 

R and C Wilson Co., 125 
World Rodio Labs, Cover III 
73 Subscriptions, 126 
73 Back Issues, 126 




Back Issue Bononza 

Curl up in your hammock these hot days with 
twenty assorted fascinating back issues of 73, 
They'll keep your mind^ imagi nation ond 
soldering iron active through the sweltering 
weother. Our choice (but a good one) at this 
low price, 20 issues for $5. 

Dottie's Speciol 

Get eight fabulous bock issues of our choice 

for only $2, 



fe Back Issues 

Indivfduol bock issues other than 1960 ones 
are 50(f. 1960 issues cost $L January 1961 
isn't available. 

Bound Volumes 

All we've got right now ore 1963 bound vol- 
umes. They're beautiful ond cost $15, 

Binders 

Binders for all veors ore available: 1960-61, 
1962, 1963, 1964, 1965 and 1966. They're 
$3 apiece ond a nuisance to wrap, so order a 
bunch at once, pieose. 

All of the offers above ore postpaid in the U.S.A. 
and Canada » Please include postage on overseas 
orders. 



73 Mogoxine 



Peterborough^ N.H. 03458 



126 



73 MAGAZINE 



•TAB" • TRANSrSTORS * DJOOES!! 

GTD* FACTORY TESTED — 

FULL LEADS. 

PNP 100 Watt/15 Amp HI Power 
T036 Caser2NMl, 442, 277, 
278, DS5D1 up to 50 Volts/ 
VCBO $1.25 @, 5 for $5. 
2N278, 443, 174 up to SOV J3 @, 
2 ror $5, 5 for JIO. 

PNP 30 Watt, 211155, 156, 235, 242, 254, 
255, 256, Z57, 301, 392, 40c@, . . . . J for Jl 



PNP 2N670/30OMW 35c @, 



• *.*■'>' ' 



5 for $1 



PNP 2N571/1 Watt 50c @. .3 for $1 

PNP 25W/TO 2N538, 539, 540, ... .2 for II 
2N103& 6/$l, 1039 4/JIp 1040 /$1 
PNP/T05 SIGNAL 350Mw 25c @, . . . S/Jl 
NPN/T05 SIGNAL IF, RF, OSC 25c®, 

Silicon PNP/T05 & TOIB 25c @,. .5 tor |1 
Power Heat Sink Finned Equal to 180 
Sq* Surface ...... . .51-50 ®. 4/(5, 10/JlO 

T036, T03, TOlO Mica Mtg 30c ®, , 4/|l 
Diode Powar Stud Mica Mtg 30c @, . ^/Il 

ZENERS 1 Watt 6 to 200v $1 ®, 
ZENERS 10 Watt S to 150v {1.25 
ZENER Kit Asstd up to lOw .... 

STABISTORSuptolwatt 

TRANSISTORS-TOO MANY! 
Untested Pwr DiamorTds/T03. .. 
Urttested T036 up to 100 Watts ^ 
Untested T05/SIGNAL/sistors. 
Untested Power Diodes, 35 Amp 
Untested Pwr Studs, 12 Amp.... 
Untested Pwr Studs op to 6 Amp. 
Untested ^^A Tophats. .....,,. . 



: 3 for $1 
10 for $1 
U-TIST 
.10 ford 
..5for$l 
20 fori! 
. 4for Jl 
J0for$l 
..18/$1 
.,25/11 



DX. Power Suppiy 115v/60 to 800 
Cys. Output 330 : Tap 165V up to 
150Ma, Dastd iSm 2 for $9 



SILICON POWER DIODES STUDS & P:F.** 

300PJV 

210Rms 

.85 

LIO 

2.25 

4.50 

10.45 



D. C. 


SOPiV 


lOOPiv 


aoopiv 


Amps 


35Rms 


70Rms 


140Rms 


12 


.30 


.50 


.70 


18" 


.20 


.30 


.75 


45 


.80 


1.25 


l.SO 


150 


2.50 


2.90 


3.50 


240 


3.75 


4J5 


7.75 


D. C. 


400PFV 


SOOPiV 


600PJV 


Amps 


280Rms 


350Rms 


42DRms 


12 


1.10 


1.30 


1,55 


18 


1.50 


2.00 


2.70 


45 


3.25 


3,50 


3.90 


150 


5.40 


6.50 


7.50 I 



750Piv 
525 Rms 

L75 

3.40 

4.50 

12,00 



IU4 Silicon Tube 
5R4 SiMcon Tube 



52 @, 6 forSlO 
$5 @, 2 for? 9 



•NEWEST TYPE! LOW LEAKAGE 

*ALL TESTS AC Ji DC 

A FWD A LOAD! 



PIv/Rms 

50/35 


Piv/Rms 

100/70 

.10 


Piv/Rms 

20Q/140 
,12 


PIv/Rms 
300/210 


Prv/Rms 

400/280 ' 
.20 


Piv/Rms 

500/350 
.25 


Piv/Rms 

600/420 
.30 


Piv/Rms 
700/490 


PIv/Rms 

800/560 
.40 


Piv/Rms 
900/630 


Piv/Rms 

1000/700 
.55 


Send 25c 

for 
Catalog 



1700 Plv/1200 Rms/7S0 Ma/$1.20 0i', 

10/$10 
Same 1100 Piv/770 Rms 75c@, 16/111 
3 Kv/2100 Rms/200 Ma/J1.80@, 6/|10 
6 Kv/4200 Rms/200 Ma/54 @, 3/$9 



Discap.002® 6Kv 

Discap .01 @ 1 Kv..... 



****»■*** 



SCR-SILICON-CONTROL RECTIFIERS 1 



PRV 

lOO 

jOO 

^00 

4300 



7A 

Q 
Q 

1,50 
2.00 



25A 



2.25 
2,90 



PRV 

500 
600 
700 
800 



7A 

2.50 
3.25 
4.00 
4J5 



25A 

3.75, 

4.25 

5.00 

5,65. 



3/51 



UNTESTED ^'SCR" Up to 25 Amps, 6/$2 
Glass Diodes IN34, 4S, 60, 64, 20 tor $1 



Two RCA 2N408 & Two Zeners 
RCA IN2326 on prtd 3^1. «/52 



TAB 



"VOLT-TAB" 1000 Watt Speed Conlrol 
IISVAC 510 @, .,.......*,. 2 for 519 



WE. Polar Relay *2S5A/55 (q, ,. 2 for 59 
W.E. Socket for ^255 A Relay, . _ . , . 52,50 

Toroids 88Mhy New Pckg 51 @, 6/55 

6.3VCT @ 15.5A & 6.3VCI @ 2A |5 @, 
2 for 58, 20 for 560 

200 KC Freq Std Xtals 5? <^U 2/53, 5/55 
Printed Ckt Bd New Blank 9x12^ $1 @ 
Klixon 5 A Reset Ckt Breaker 51 m, 10/J5 
2K to 8K Headsets Good Used 53 @, 2/55 
Finished Xtals Asst Types 20 for 51 



Battery Charger 6&12V Charges up 
to 5 Amp ''Approved" Heavy Duty 
Design with Klixon Circuit Breaker. 
Operates 220 or 110 VAC @ 50 or 60 

Cys $10 @, ■ ■ 2 for 518 



■ WANTED TEST SETS 

A EQUIPMENT 
Bandswitch Ceramic 50OW 2P/6Pos $3 (g^ 

5Hy-400Ma Choke 54 fe, . . - -2/55 

6Hy*500Ma 55 @, ...,..,...*....... .2/56 

250Mfd m 450 Wv Lectlytic 4/SSB S3 (a> 
Cndsr Oil lOMfd t 600 51 («*, . .4/53, 12/55 
Cndsr Oil 6Mfd m 1500V 54 @t.,. 5 for 510 
880 Vcl@ 735Ma for SSB 512 m, , . . 2/522 
460 Vet (m 40Ma A 6.3 ia\ 1.5A CSD 51.50 
10 Vet @ 5A & 7.5Vct @ 55 fei ^ ^ 2/59 

SILICON TUBE REPLACEMEN'tS 



0Z4 UNIVERSAL 51-75 friv, .4/55 

5U4 1120 Rms/1600ltiv 52fa., . . . ,6/58 
5R4 190O Rms/28DOInv 56 fe^, . 2/510 
866 5Kv/flms - 10.4Kv510@, 3/527 



20VAC & TAPS/B, 12, 16, 20V i<h 4A, J2 @, 
32VCT/iA or 2X16 V iB iA, 55 0^, . , . .6/524 



Line Filter 4.5A @ USVAC. ,.,.., 5 

Line Fitter 5Airo) 125VAC 3 

Converter Filter 400 Ma fm 28VDC 8 
Converter Filter lnput/3A('r30VDC 6 
866A Xfmr 2.5V/10A/10Kv/lnsl 
Ballentitie #300 AC/Lab Mtr,, ...... 

Choke 4Hy/0.5A/27S2 53 m^ - 

"VARIACS" L/N 0-135V/7.5A,..,-* 
"VA Rl ACS" L/N 0-135V/3A ........ 

TWO 866 A's & FIL Xfmr, 



for 51 
for $1 
for 51 
for 51 

...545 
.4/510 
. . . 515 

. .510 

....56 



RUSH YOUR ORDER TODAY. 
QTYS LIMITED 

Wica Condsr .006 C^ 2500V *,. 4/51 

Snooperscope Tube 2** 55 @| .....,., .2/59 
Mini -Fan 6 or l2Vac/60 Cys 52 @,. - 3/55 
4X150 Ceramic Loktal 5L25#, _.._4/52 
Line Filter 200 Amp/130 VAC 510®, .6/550 




....2/55 
.,..2/59 



DC 3Vi' Meter/RD/800Ma 54 
DC 2^' Meter/RD/lOOMa 53 
DC 2bi" Meter/RD/30VDC 53 
DC 4* ileter/RO/iMa/SSQt 

WANTED 
LAB METERS! BRlDGESt 

Wodulation Xfmr 60W/15K to 5.7K 55 

Socket Ceramic 1625 Tub«, * . , 4/51, 10/52 
Socket Ceramic 866 Tube. , . . .4/51, 10/52 

Socket Ceramic 4X1SO/Loktal ,4/52 

Wanted 304TL -Top 55 Paid ! I 

WANTED 

YOUR - ORDER - TODAY! 

2.5M H PiWound 500Ma Choke ... .3 for 51 

Knob Spin -Crank BC348 51 <<ih - « ^-3 for 52 
MinlFan 6 or 12 VAC 5L50 m, ... .4 for 55 
Beam Indicator Seisyns 24VAC. . .2 for 510 

Precision TL147 Feeler Reiay Gage $1 

Fuse 250Ma/3AG 50 for 51, 300/52 

DON'T C'WRITE & SEND ORDER! 
XMTTG Mica Condsr M^ C^i 2.5Kv ,2/51 
Mini-Rectifier FWB 25fta @ 115VDC 
3 for $1, 20 for 55 

W€ Buy^ Sett A TradM 
1 I I SEND 25c FOR CATALOG f I \ 
,j^ m ■&■■ T«rms Mm. Onfer $5 
**TIIIl'' FOB New York 
I HD Our 23rd Year. 

UlTA Liberty SL/ N.Y. 6, H,Y. .Re 2-6245 



Micro-Switch Rated 40Amp AC & DC 

SOc(^i, 5/52, 20/55 

BandPass Filters 60 or 90 or ISOCys 

3 for 55 

"Brunlng" 6' Parallel Rule @. , . * — .%l 

Linear SawTooth Pot KSl5l38/W. E, 

5 or 51 ^ ,« 

2V3G Tube HiV Rep! 2X2A , . 5/tl 

"SPERRY" Waltmtr Meas. LoPwr RF Self- 

Calib/SOMuW to lOMW 510 

Synchro Differentials C78249/115VAC 60 

Cycles Less Back Plated, •.. 55 

Bendix Auto Syns VAY ' Series 2/52 



PL259A & S0239 CO-AX M&F . . 

Phone Patch Xf mrs Asstd 

FT243 Xtals & Holders ...... 

Jnsltd Binding Posts , . . 

Sun 'Cells Selenium Asstd 

TO36/100W Untested Transistors 



4 * ff B > 



3/52 

.3A1 
. 2/51 

20/51 
6/51 

.3/51 



Tube Clamps Asstd • . .f /SI 



,01 Mica 6O0WV Condsr 

.001 to .006 Mica/lZOOWV Cdsr . . . 

DiSCAPS.002<f/ 6KV 

DISC APS .005 (m IKV 

DISC APS .0012 (ai 6KV , . . 

DiSCAPS.OKrfaKV 



. • i » » 



6/51 
4/51 
3/51 
10/51 
4/*l 
,6/51 

. .3/55 

... is 

.52 

h ■ ■ ■ -r -^^iL 

.3/510 
-.5/55 



Stevens Precision Choppers 52 @, 

H el i pots Multi Ten -Turn (§^, , 

Precision 3-Turn Pot @, . - - — ^ ^ . . 
Precision One-Turn Servo Poi@t* 

Helipot Dials 54 (« , * 

5 Gang Servo-Pots 52 @, ■ • . > 

Snooperscope Infrared Tube Image Con- 
verter HiSens 2' dia, HiResolution up to 
350 Line/in 5S fe, - ^ for 510 

Vibrator Special Asstd ,*.3/51 

Crystal Oven & Holder -42 

THERMISTOR-VARISTORS - W. E. 

D167019 Vol Limit 53 if^'. .5/510 

D168391 Therm Coup. 51®, ,10/55 

0168392 Therm Coup. 52 @, . . , 6/55 

01703% HF Pwr Meas. 52 @, 6/55 

IC Bulb Time Del. ...,.,. .2/51, 15/55 

38C/20259 Bridge 54 ®, 4/510 

Mold Scope DuoDecal Socket — 3/51 

Molded Diheptal Socket .3/52 

Ceramic Maginal Socket .... .... 4/51 

Octal Molded * * * ^^vlJ 

Octal Ceramic .,.♦*..........**».. .10/51 

304TL or 829 Johnson Socket ..,......* .51 

X-Formers All n5V-60Cy Primary- 

2500V (fi\ lOMa S Fil 52 @, ...... .3/55 

llOOVCT <u 300Ma, 6V @ 8A, 5V & 3A & 

125V Bias, abt 1200VDC 55#,.. 4/515 

2.5V iti^ 2A 51 ^<t ,,..._,. 3 for 52 

6.3 V(ci* lA 51.S0(a, „. ...,4 tor 55 

M77 Tube Hfckok Type Checker 539 

G- E. YYZ-1 Decade Scaling Counter & 

Dual Channel & Meters ......... . 545 

Pirani Vacuum Gages , 539 

"ESC" Var. Pulse Ten Step Delay Network 
TD. 5USEC/Z100Q 4 .05 to ,5 , - .536 

AM TIME PROD 500 cys Fork Amp $33 

*'VFC" Vibrator Feeder Controller 

Type 5— (Shake Table) .5100 

Black Light Lamps/UV 52 

Osram Mercury HflOlOOW/2 

Hilntensity DC Lamps — 520 

Osram XBO450W/P Lamp 550 

G. E. )!?190T3/CL-60V/Q-lnfraR Lamp .^lO 

Tuning Unit BC746 Make 

Bantam 1 Watt less Coils J/S2 

Welch Duo-Seal #1402B Lge Cap Hi Vacuum 

140 Ltrs/M & Mtr \..*.. 5200 

ConsoNdated Vac. Corp PMC115A Dif- 
fusion 'ION Pump ^ . -5125 

HiVac Valve CVC#VCS21@, ,,.*.S75 

Temescal VAC Valve®, 512 

Electronic VAC Deposition JAR tess 

Glass Bell 6^^ I D 5100 

WE. jfc293 Spring Relay Tool ....2/51 

CD307A/6Ft Ext Cord PL55 Si JK26 , . . 51 

Carborundum Fine 6" Stone — 2/51 

Binding Posts 5W3y/30Amp R&8 5/51 

Tubes 6AG7 or 6AC7 3/51 

WANTED TUBES ALL TYPES 
We Buy, Sell A Trade As Well! 



OCTOBER 1966 



127 



wm 



^ 



r 



ELECTRONIC TECHNICIANS 



As long as jouVe moving np 

to R&D 70U mightf 

as ivell be choosy about it. 






And at Sanders there are quite a few things working for yoii» 

In the first place^ yoa choose yonr own technical area* And 
you^lI Bnd lots to choose from: microwaves, ECM^ instru- 
meats and control systems, electro-optics, data handling 
equipment, video display s, power supplies^ environmental 
studies, standards and calibration^ RFI, special test equip* 
nient. You pick il — that's the field you work in. 

Another thing is how you do it. You'll he assigned to a three* 
man team — ^two technicians, one engineer, setting up proto* 
types. It's raosly breadhoarding, always somelliing new, never 
dull, or repetitive, What's more, you don^t gel a last shuffle 
at Sanders — once youVe picked your technical area, that's 
what youll be doing. 

If you're just out of tech school, or the service, a good grasp 
of theory and fiiiidamentals will get you in 011 this deaL 
And if you already have a couple of years of experience, 
you'll do even better. 

Our tecliiiician salaries are high- As for benefits and working 
conditions, you can't top them anywhere around. And we're 
easy to gel to, just 30 minutes froni suhurban Boston. 

Interested? Drop us a line, outlining your background, work 
experience^ and salary requirements* Address Mr, D. A, 
Williamson. 



Sanders associates, inc 



NEW DIRECTIONS IN 
ELECTRONICS SYSTEMS 
Nashua, New Hampshire 

An Equal Opportunity Employer 





12s 



73 MAGAZINE 



1967 CATALOG 




BARGAINS 





JUST MAIL IN COUPON! 



From WRL — fhe fa rgesf and most personatized 
Radio Supply House in the Wortd. 35 employed 
Horns to assiit you with your amatBUt needs. 



ALL NEW* . . 1 00 pages of excit* 
ing equipment ond accessories* 
Completely illustrated* 

• The most complete cotolog for 
Hams and CB'ers ever put to* 
gethen 

• Detailed illustrotions. Complete 
specifications. Save at World 
Radio Lab's amazing low pricesf 

• See selected best buys on Ro- 
dios, Recorders, etc* 



Special purchases for Electronic 
Builders. 



Buy anything in the catalog on 
our easy, monthly credit plan* 



"The Heust the HAMS Built" 



CLIP AND MAIL THIS COUPON FOR YOUR COPY 




I^eo L Meyerson 

W0GFO 
President 





S WORLD RADIO LABORATORIES 

■ 3415 We*t Broodway 

S Council Blufft, Iowa 51501 

Gentlemen: 

Pleaae rush me my FREE 1967 WRL Catalog. 

Name : 



73-101 



Address 



City 



State 



Zip 



WK 







• * - * 

• t 




il% 



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